I have used bow cavalry in STW2 and it is precisely the micromanagement that is the problem.

In legendary SP you can't issue orders while paused or slow the speed so this isn't really a practical option - much preferred Rome and Medieval where you could leave your stack of horse archers on skirmish and go off and make a cup of tea knowing that they'd probably have destroyed any infantry army by the time you'd finished.

I have started adding two katana cav to my mid-game killer stacks though and one notched up 775 kills chasing rioters so more than justified the cost.

Also experimented with a half stack of bow and katana cav to raid enemy castles behind enemy lines but they didn't last very long....