Originally Posted by Austinrunner

Tweak and retain all you want during the hold. Just know that when you give up a held seat, it might or might not go back into award inventory for someone else to book.

Originally Posted by aktchi

You can make date changes to individual legs not only during the hold but also after ticketing.

The most convenient use of hold, besides deciding if you want to take the trip at all, is to tweak your itinerary, ie, change airports and airlines. During the hold, you can do it leg by leg. After ticketing, you cannot do it at all.

On the last day of the hold, you should call and ask if they can extend the hold. This requires entire itinerary to be available outside your own reservation. If it is, and often that is the case, you can start a new hold. If not, you have to decide whether to ticket that day or let go.