Yeah, I was exaggerating but really, you're talking about maybe an extra 30 minutes once a month if you do a pretty thorough cassette cleaning? Your time is scheduled so tightly and is so limited that you'd base a decision on that, rather than the riding experience for the hour+ per day you'll actually be spending ON the bike? I say that as someone who predominantly rides fixed, but also as someone who has learned how to adjust derailleurs and clean cassettes and keep geared bikes running well just by reading sheldon brown and watching some youtube videos and it's just not that hard.