I'm happy to bang out thousands of lines of code in sessions that last hours on end. The first two lines are always

use strict;
use warnings;
[download]

But I'm just too lazy to type -T on the command line. Weird.

But in all seriousness, in my personal programming style, I don't want anything as strict as taint checking. I write most of my code for myself, to run as myself. You could say, "turn it on if you're writing a server," but if you really care I would say that as, "turn on taint if you're accepting input from someone else." Servers, scripts running under servers, or clients communicating with other clients.