I've stopped over-thinking it. If I'm tired I sleep and don't if I'm not. I don't force myself to sleep or stay awake.

Much of what is attributed to jet lag IMO is actually the result of disrupted sleep schedules. There is a significant difference, for me at least, between an overnight YYZ-LHR and the daytime flight. I'm much better rested the next day if I don't fly overnight.

If I have to fly overnight I take the latest flight possible. I will be more likely to sleep and can go directly to my hotel upon arrival for a nap instead of having to contend with a few hours before check-in time.