Its a loosing battle. Don't think about it or you'll loose your mind. Its a no win situation.
Myself, I work very little, and have plenty of time, but I don't think its much fun to just stare at a screen in real time for hours upon hours without nothing going on
... so its not just a matter of having time. I mean, what good is "playing" at 1xTC if you're watching TV or reading or something else?... that's not an "inmersing" experience, is it? You hit the nail right in the head when you mentioned that there just isn't anything to do in the game to kill the time.
On the other hand, you DO need to ease off a bit on the TC. Myself, I'll never go higher than 256xTC, since it is generaly beleived that going higher affects the game's performance relating to contacts.
In dangerous waters (surfaced under heavy allied air coverage), I tend to play at 64xTC... I like that one because it takes 1 minute to simulate one hour (more or less), so it's a nice balance between the need to speed the game up and the need to guard yourself against "sudden" surprises from enemies.
During combat maneuvers I'll play at 1xTC, since it's pretty easy to get killed even on low TC settings such as 8xTC (the game doesn't give you the same audio warnings as in 1xTC... depth charges won't sound, for example.
You'll just have to figure out something that works for you... good luck
