My favorite technique is to write a quick script to find all the subroutines and insert a print "\n..subname\n"; statement as the first line. (The double dot at the start of the line makes it easy to grep for, as I don't start any other messages with it.) Then I go and do other things with the code, like fixing a few bugs, or tuning a feature. And each time I run the code for a test, I remove the print statements that I've seen. Not necessarily all of them, because that can be tedious, just the ones that "annoy" me the most. (Usually the most frequent ones!)

Then after a month or so, I rename all the functions that still have the print in them. (I normally prefix them with a 'z' so they sort to the end of the list. Easy to find 'em if I want 'em, and easy to ignore them when I don't want to see 'em.)

...roboticus