It takes like 5 minutes to render every frame, at least in Revit it can, so I guess work from there you don't want to wait days.
15 frames per second is fine too.
In my opinion 30 frames per second is good.
We normally don't export animations from Revit; we use Navisworks. We usually export those at 16 fps. Anything below that would cause the video not running smooth. While some people would argue about 16 fps being less than required, we have found this quite satisfactory and have created many animations for several clients with totally smooth and watchable videos.