So I’ve been seeing advises like “Just take the most rigorous courses offered at your school” etc etc, but if my school offers something like 20 AP courses, and I’m only taking 7-8 of them, would that be considered rigorous or not?
I don’t think I can really take 10+ APs in high school like most people are doing. 
Would not having a rigorous schedule hurt my chances at top 50 schools?
You should take as rigorous a schedule as you can handle, if that makes sense. If you can only manage to take 7 or 8 AP classes and still get good grades, then do that.
Ask your GC if they would check the “most rigorous” box on your college applications.
Don’t compare yourself to people on CC when you are applying to colleges you will be judged based on the resources you had available and what you did with them. No college expects you to take 10+ AP classes.
here is a handy thing http://mitadmissions.org/blogs/entry/on_aps_1