in reply to removing "use strict" eventually

There's a famous observation to the general effect:
The last bug has been eradicated when the last user stops using your program.

Leave strict and warnings in!

Contrariwise, in the case of a web page or ap, you probably do want to remove/comment out instructions like use CGI::Carp qw(fatalsToBrowser); because if you leave them in, you may give more help than you intended to someone trying to develop an exploit.