The pinbox level was one of the first things I put on our "new" trailer when we got it home.
I have found that eight or nine times out of tem I can find a side-to-side level spot without getting out of the truck and thereby avoid having to mess with blocks at all.
I carry blocks and if necessary will use all kinds of combinations to get it leveled, but if I can do it by just moving forward or back a little (or even a foot or two to one side or the other) to get out of others wheel ruts I'll take it every time.