Depends on your environment really and how you're deploying. I've management many SMS\SCCM environments at quite a few different companies and it varies at every place.
The better your network and desktop standards are, the better your success rate will be assuming your package and deployment was well planned and tested. Some places 90% was a good success rate, some places 95-98%. Also make sure your database doesn't have a ton of old data and you have an accurate target count.

I base all my deployments off a collection that contains only machines with a heartbeat in the last 30 days.

If it's going to take longer to package and fully test an application than it would be for the local IT to manually install it, I won't package it. I'm going to assume your talking about a in-house developed app or something really old. VM's and snapshots are your friend if your doing this yourself.