I was afraid someone might ask what "short" and "long" are in this context, as well as "a few" and "many".... Those are ambiguous quantifiers. Reminds me of my economics classes when professors talked about "shortrun", and "longrun".

I think that the experts (such as Friedl, in MRE) intentionally don't try to define what is short, long, few, or many. I won't try to second guess their caution about defining thresholds. But I think it's safe to say that in the context of study, a few thousand characters is pretty short. However, the only way to be sure is to benchmark it. And as I implied, bothering with study at all should be a last resort, after exhausting other design options.

As for "literal text cognizance", the very following sentence defined it: "Without a known character that must appear in any match, study is useless." Literal text cognizance means that unless your regexps are looking for literal text within the string (as opposed to only containing "wildcard" matches), study is useless.

.....in other words, if your RE contains ONLY the "wildcard" matching constructs such as ". \w \d \s \S \W \D", etc, and doesn't contain literal text, you're wasting your time with study.

...for example (warning; silly examples):

m/\w+\b.?\d*$/; # wouldn't benefit from study.
m/abc/;         # may benefit from study.
m/\d+abc\W.+/;  # may benefit from study.
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