Henk,
I think that if we want to improve this, we should first define what an acceptable time for a response from an author (or AD) is.
Yes. The IESG talked about new stretch goal times for the time between publication request and draft approval. These would be 6 weeks for drafts without changes and 8 weeks + any author time for others. In addition, when the draft enters a state where we are waiting for the AD to do something, we'd like to see some action within two weeks.
I think two weeks would be a good default maximum time for authors to respond or react with a new document version.
Of course, there are special cases that will go over these times for various reasons. Vacations and difficult document changes, for instance. And I hope most interaction actually happens immediately; same day responses seem to lead to immediate action on both sides. If everyone responds exactly in two weeks, the RTT in the discussion will be 1 month :-(
Jari