SEO and the impact that any work has is not about length. Sure bloggers have echoed that blog posts should only be about 300-350 words, then 500, and so on. At one point, search engines rewarded blog posts as being timely and these posts were easily found by it's length. Then it was discovered that the bounce rate of blog posts was significant. The reason was simple to understand. Most blog posts were "me too" posts, short, stated little in the way of facts, ideas, or solutions. Generally blogs offered lousy content overall. Then the whole notion of longer posts was all the rage except that they did not perform so well either. Posts had become too long in an effort to chase an imaginary metric.
So what is the answer?
Any content that grabs the users attention and retains it, provides good detail without getting too far into the weeds, offers a specific solution to a specific problem, can back up their assertions with solid facts, and sparks the imagination of the reader and allows their mind to wander and wonder, will do well. Period.
If yo do this, then your content is the perfect length. It is about pleasing users more than machines.
It is also about semantics. Longer pages that do not focus well on a topic and wander around too much will give diluted semantic metrics. Each page must make sense topically and not go too far into other areas. It is a skill to cover a topic narrowly enough without short-schrifting the potential.
It is too broad of a topic to get into semantics here, but what you will see is that each content segment will be analyzed to determine topic both broadly and narrowly and given a set of scores that are then used to match the semantic analysis of the search query. To overly simplify the process, these scores are matched using algorithms. No where in the analysis is there any metric for content length. Just the strength of the content for the topic sought in the search query. Where this works best is for well written search queries where semantic analysis yields accurate topical results. These are more than one or two terms and contain a subject, predicate, and object. In this way, intent can be analyzed.
So again, content length has nothing to do with search performance. It is the topic of the page and how well it is covered and whether or not you are like me and tend to ramble on a bit too much and have to edit your work.