What percentage of active projects are "on hold" at any given time. We are close to 10% and I believe that is too high.

I believe that is too high too, but I dont know your business or how it works. Maybe in your line of work, that's normal.

Often, people will enter jobs way before they're ready because they're trying to "get ahead of it". It usually results in more work having to go update everything when they finally activate the job.

Clients do delay jobs and put things on hold often. If it were me, I would investigate quite a few of them first to find the reason for it.