MTT Timeclock management/strategy question

Ok, I play lower level MTT on Iggy ($5-$20 entry fee). I have been successful at that level, but I am a piker compared to many of you. One thing confuses me. The last few months, even early-on in tourneys, it seems there are 2-5 players at every table who insist on milking the time clock every hand (and often every card). Why? What strategy am I missing? I know later in the tourney you have players delay, hoping other players drop out so they could finish ITM (or higher if we are already ITM). But are there other reasons? Perhaps playing many (too many?) tables? Other software? Insights please.

Mel