Learn English – Does “avail” make sense here

This is an interesting question, because the first thought is to explain it to you a terms of programming methodology. But your question is about the language used in the statement:

The point here is you want to be as specific as it makes sense to be every chance you get.

Let me give some context of my own, first:

Cascading Style Sheets allow you to define styles in a hierarchical manner, relying on the higher levels to define a set of styles that apply to a broad range of rendered elements. For instance, you may specify overall font styles, including font type, font color, and font height, as examples.

At the lower levels in the style sheet definitions, you may modify the styles for more specific elements. So you may want to change the font weight for an element, to emphasize a word, for example.

What your sentence is telling you is that you do not need to respecify all of the other details. Only specify the style element that is needed. This is what would make sense. This is all that is necessary. To do otherwise would (or may) create additional work, it would be unnecessary (obviously), and may even lead to other unexpected problems. To specify elements that have been adequately defined at the higher level would not make sense. There is no reason to specify style elements that are already specified the way you want them to be. (But you should respecify those that need to be changed.)

So to make sense in this case means to be reasonable or logical.

The point being made is that you should only be as specific as it reasonable (or logical) to be. Do this every chance you get.

While I don't discount your question entirely, I should warn you to be careful interpreting the data. At least part of the rise of caffeinated could be due to the recent popularity of caffeinated drinks, whose caffeine content may be artificially introduced. I think we can agree that the use of caffeinated to describe the result of artificial production processes is uncontroversial.

However, "naturally caffeine-bearing coffee" isn't a very convenient phrase. It seems logical to introduce an antonym to decaffeinated through back-formation by dropping the de- prefix, even if it doesn't make complete etymological sense.