Its different for each airlines. For Japan airlines, once you create the account, you have to wait for 60 days cooling period and then only you will be able to redeem airmiles. There are 3 options for award tickets in JAL site.
1) JAL award tickets - For their own flights only
2) Partner airlines - There are list of partner airlines and we can select the desired one.
3) One world award ticket - in this, single itinerary may contain different one world airlines.
Highlight: For JAL miles redemption, we can add one stop over for free, that makes JAL special compared to others. In my recent trip, I had a stop over at Doha and explored one more country for free of cost. There is no restriction of number of days in a stop over.