In addition to Matt's reply, we are adding a couple of new features into the next release of Collector (iOS) that I think will help in satisfying your need:
1. Recent Values - we will remember values you enter into text and numeric fields and when you tap to enter a value you can then choose from recent values you entered previously.
2. Updating attribute values for multiple features - you will be able to tap on several features and then update a common attribute for all of them at once.
We should be releasing this update early in January and we can get you beta testing if you like.
Thanks
Jeff