I do know some people who have competed in both Wa-Wachusett & Nosnowba in the same season, so you would not be alone. Some people even compete at WaWa on more than one night!
The course is usually open by about 6:00, and taken down by about 8:00. First-come/first-served: no start order. Lines can be bad early in the evening and early in the season. You can take post-race "fun/training" runs - just give 999 as your number and they'll know what it means. Sometimes they announce that such runs should not be taken b/c of the lines, but then again, why would anyone wait in a long line for that anyway?
Typically I try to get on snow around 5:30, take some warm-up and inspection runs, then my two race runs. After that, maybe ski around with friends a bit, then extra training runs, or help out slipping the jr race course.
On Thursday nights, liftlines on the two high-speed quads are often long in January, less so in February, and almost always pretty minimal by around 8. (I suspect that Monday is relatively quiet, although Tu & We are probably pretty similar to Th?) Always very bad if snow has fallen in Boston or Worcester or Providence during the week. (Get there early or else you'll have to part in the satellite lot and take a shuttle bus - on those days I often leave right after my race runs.) Lower quad serves the race trail and other flat stuff, although riding the lift over the terrain park and watching the jibonkers almost kill themselves can be amusing. Upper quad has three trails: one is designated slow so essentially off limits, another is ok (has a mogul field that can sometimes be pretty good), and another is quite decent but often closed off from 6-8 on Tu & Th for the jr race team.
However, the expansion area triple lift that serves the upper lower mtn, although not very speedy, and just lower intermediate terrain, NEVER has a liftline - ironic that they spent so much $$ fighting crazy enviros to put in a lift that nobody rides, but at least WaWa now has a pleasantly quiet part.
I assume the lodge is always crowded, although I never go in there. (Removing the Dobermann's on a sub-zero night in the parking lot often requires several tries and puts me on the verge of tears.)
Overall, compared to Nosnowba, I think Wachusett is in a different category altogether: much more of a real race course and real ski area, even if it does have its many shortcoming.