Say I'm going to link to another site using the phrase "banana split and chocolate sauce". Is my "vote" evenly split between "banana split" and "chocolate sauce" or is this much weaker than if I had just voted for "banana split" in the first place?
I said in the comment that it doesn't matter. What I mean is the difference is so small it's not worth worrying about.
If you link to a page with "banana split and chocolate sauce" then the page can be returned for any of those 4 keywords. If you linked with "banana split" then a search for "chocolate sauce" would not return that page unless it has those words somewhere else. (And if those words were on the page, that would carry more weight that one in-link.)
Whether the query "banana split" would favour the longer or shorter link text is pretty much impossible to discern.
You could try testing it by linking to two pages with those two variations and see what comes on top (using