Okay. I have clearly confused some people. I will try and make that right.
My point is not to think about the keywords you want to be found for and just plug them into your content thinking that is the total answer. Sure, terms are important, clearly, but keyword matches is not what search engines do. I will give some examples and may go the long way around the barn a bit. Please stick with me.
Here is a paragraph from Wikipedia.
The Chevrolet Corvette (C3) was a sports car that was produced by
Chevrolet for the 1968 through 1982 model years. Engines and chassis
components were mostly carried over from the previous generation, but
the body and interior were new. It set new sales records with 53,807
produced for the 1979 model year. The C3 is the third generation of
the Chevrolet Corvette, while the 1963 through 1967 models mark the
second generation of the Corvette Sting Ray.
Here is how key terms fit within the topic hierarchy.
The content is analyzed using ontologies, in this case a topics ontology, where recognized terms are analyzed for topics.
Here you can see Chevrolet is associated with car using another ontology.
Using TextRazor, you can see more.
Here is a list of how information is found using ontologies.
Chevrolet Corvette (C3)
I have cleaned up the list a bit. The point being how terms are understood.
Here is a list of topic scores.
1.00 Chevrolet Corvette
1.00 Chevrolet vehicles
1.00 General Motors vehicles
1.00 Automotive technologies
1.00 Rear-wheel-drive vehicles
1.00 Vehicle technology
1.00 General Motors marques
1.00 General Motors
1.00 Transportation engineering
1.00 Sports cars
1.00 Road vehicles
1.00 Artificial objects
1.00 Manufactured goods
1.00 Vehicle industry
1.00 Electric vehicle manufacturers
1.00 Private transport
1.00 Car body styles
1.00 Product introductions
1.00 Motor vehicles
1.00 Wheeled vehicles
1.00 Automotive industry
1.00 Land vehicles
1.00 Cars of the United States
1.00 Automobile layouts
0.99 American brands
0.94 Car brands
0.82 Transport economics
0.72 Automobile models
0.69 Chevrolet Corvette (C3)
0.69 Motor vehicle manufacturers
0.55 Car performance
0.52 Motor vehicle manufacturers of the United States
0.49 Sports car
0.45 Muscle cars
0.42 Light trucks
0.42 Car manufacturers
0.40 Station wagons
0.40 Front-wheel-drive vehicles
0.35 Luxury vehicles
0.35 Off-road vehicles
0.35 Commercial vehicles
0.33 Full-size vehicles
0.31 Ford vehicles
0.31 Four-wheel drive layout
0.31 Vehicle manufacturers of the United States
0.30 All-wheel-drive vehicles
A score of 1 is strong and anything less is relative. Because this is a short paragraph, there are a lot of strong scores. With longer content, this would change. This does not mean that shorter content performs better in search, it may or may not, it does mean that this example is limited in scope and one reason why I used it.
Taking a subset of the topics list, searches for:
1.00 Sports cars
1.00 Motor vehicles
0.49 Sports car
0.45 Muscle cars
...can potentially match this list. If for example you want be found using
Muscle cars, you can add the terms 'muscle cars' or simply write how the Corvette 427 and 454 are muscle cars and compare them to other muscle cars of the period. You can possibly increase being found using
Roadsters by comparing the Corvette to the AC Cobra, the MG, the Austin-Healey, etc. You can also simply use the term.
While this may not be the best example out there, you can see some associations exist beyond any keyword. In this case, the paragraph is short and limited in scope. When you analyze larger content, you will begin to see opportunities to strengthen your content by making the content better and not just place in a smattering of keywords which would not move the needle much in topic scores.
As for links and other smaller segments of content, the fuller semantic the segment of content is, the better. For example,
Chevrolet Corvette (C3) is fine, however,
The history of the Chevrolet Corvette (C3) American performance sports car. is far better. Not because I added some keywords, yes that helps, but because it is fully semantic with a subject, predicate, and object. Adding
history increases the topic scores in other areas if your content is about history. If the content is about design, then
How the designers of the Chevrolet Corvette (C3) American performance sports car conceptualize the process. Please note that it is not necessary to put
performance sports car in your work since topic scores for these terms exist. To increase being found by
performance, you can simply talk about the performance of the Corvette.
To answer the question as to whether topics are a product of a well structures site, the answer is Yes! But it is also more. Any well written content focusing on clarity, completeness, expertise, etc. along with organization that signals what the content is about, both structurally and using links, strengthens the topical scoring.
To answer the question as to whether linking from pages of a different topic will help of hurt SEO, this is a bit trickier.
Once you get a feel for how terms fit into topics, you will quickly see that some topics are complimentary and sometimes obvious. The example of pot roast, wine, and chocolate cake are all complimentary, it is easy to see these are foods, but these are also topics about baking, roasting, etc. If you link between pot roast and leg of lamb, these are closer because they are both roasting which is a method of cooking meat. However, linking pot roast to cars is inadvisable. The topics have to be relevant.
My point is this, keywords often do little where as tweaking content to add strength does far more including how searches find your content which is ever evolving. As long as you stay within topic. For example, you can add content about other car manufacturers and still be within topic. The first image shows a fraction of the hierarchy. Chevrolet comes under vehicle manufacturer. Comparing the Corvette to the Mustang at the time works on multiple levels of the hierarchy and will strengthen the topic score because Ford is a vehicle manufacturer, the Mustang can be a muscle car, certainly the Mustang is a performance car, both are two seaters, both are sports cars, etc. However, if your content is about Corvettes explicitly, then a mere mention of the Mustang is enough. You do not want to dilute the topic of Corvette.
Are you getting my drift?
As English speakers, we are trained poorly for this. We use far too many pronouns and make assumptions that readers know what we mean. However, a good writer has been trained to avoid such traps and be a bit more explicit. When content is clear, thorough, and most importantly desired, then it will be found. There is no need to guess what search terms are used, and remember this changes daily, and insert keywords awkwardly to compensate. Strong content wins the race every time.