Maybe it's because I'm lazy or maybe it's because of my experience in working on teams. If a person is absent, they are absent regardless of the reason. They weren't there and didn't participate so the team had to work without their contribution. If they miss the the iRAT but make it in time for the T-RAT then they can get the T-RAT grade. If they miss both, they miss both. I used to put iRAT's in the Testing Center and give them a week to make up but it was way too much trouble and counter productive. For one, by that time the team had completed the T-RAT was ready to move on. Secondly, my classes have always set the iRAT as the lowest level so we're talking about 5-10 points here (out of 1000 possible). Then, I had to put the test in the center, go back to pick it up, do additional grading, etc. So, I changed and the only make up if you miss the iRAT/T-RAT is to do an article review related to the application exercise. All my application exercises are researched based. Since students have to read the articles anyway, doing a two-page write up is one way to get them deeper into the topic and is something that could be valuable to their team. Incidentally, it's also the only extra credit I offer. So they could make up their points that way.
Since we're talking about absences, I have found that conscientious student tend to do a good job of communicating with their teams when they miss and maintain their part as team contributor. I had one student who was pregnant and missed on the day of the discussion of the application exercise but she had put such work into helping the team prepare that they all gave her a bonus on the peer eval. So I challenge my students when they are out to apologize to their team mates then keep in touch and participate as such as they can in helping the team complete it's work.