testpanel,
Like others here i spent years in the air controller's seat trying to transfer a/c to area control at the best possible time time for all concerned.
I also spent time as 'the catcher', receiving traffic transferred to me from the ladies and gents in the tower.
One of the SIDS usually required...."After passing 4000 feet, turn right heading xxx degrees climb to FLxxx, there's no ATC speed restriction".
It was hard trying to stop u/t ATCOs giving pilots all of this stuff 'in one go'.
It's a fairly high-workload time for all of us, and I suspect there is no easy answer to it.