Do you boil your lasagna noodle sheets pre assembly or let them cook in the oven after layering?

Depends on the noodles. They do make a brand that you don’t have to boil prior but unless it’s that brand I think you usually have to boil them.

My family has always boiled before putting together and popping in the oven

I don’t boil

I use the brand you don't have to boil first. I find it's a lot less time consuming.