Without 2xbonus, I've to do warm up-pass go shoot-piggy-skill drill-use your head-stretch 4 times with a 16-man team. It usually fills up the possession and attack bonus from 8% to 10%. After that I do warm up-video on all the players (or omit very tired players sometimes); it fills up the little remaining condition and defence bonus.
With 2x bonus, I skip the warm up-pass go shoot-piggy-skill drill-use your head-stretch once.
Very odd, but possession gets maxed in only 3 sessions for me.