Tire question. Are all allotted tires pre-mounted on rims for the entire weekend, or are there mechanics feverishly mounting tires on the spot?

Bonus follow-up: are the wheels balanced in traditional fashion, or are the quality levels of tires/wheeels high enough that balance is a non-issue?
Submitted August 11, 2018 at 10:56AM by rmsdisplacement https://www.reddit.com/r/motogp/comments/96fhtc/tire_question_are_all_allotted_tires_premounted/?utm_source=ifttt