This is a practice hence the laidback and slow-paced fashion.
This double cross-arm install and removal is a timed competency (comp). You have 15 mins to climb up and install ONLY. You call time to the instructor when you think you're done, and all your square washers better be square and straight! (There are 10 of those by the way). Although the time has stopped, the comp does not end until the arm is completely uninstalled and you climb down. As you're uninstalling the arm, you cannot drop ANYTHING (doing so will result in a failed comp). The comp is being graded from the moment you leave the ground to the moment you return, and the time is just for the installation part. Also, every piece of hardware that is part of the cross-arm must be sent down via handline (rope & pulley). If you bring something down in your bag, it's a failed comp. Your groundman can make or break your comp, as long as they send up your stuff in the right order and orientation, you'll be good! Enjoy! Hey Pops!