Actually, don't some carriers have a rule that seatbelts fastened whilst seated at all times is mandatory? Isn't that a Lufthansa policy?
Incidentally, as a FFFFFFFFP (note the number of F's), I always wear my seatbelt whilst seated. I fail to see what's so difficult about it. Over the blanket as well! It's easy! Nice and loose, but nonetheless capturing, if you know what I mean.
What do you mean about the "leans"? What is that exactly?