Not sure if I'm misreading or you don't quite get it.

Say you have RSV M-F but the Sunday before you start reserve you have listed for VDO. CM calls Sunday and has a 4 day (typically leaving as soon as you can get there. You get VDO for all 4 day even though 3 of them were already RSV days. The one day (Sunday) is repaired as a day off. Usually next available day, which would be Thursday but they might swap it for Friday since it would be one day off and one day on call, or you can negotiate for a different day.
Or you can ask them to not restore the day off for 4 more hours of add pay.

Now same days on RSV but you listed your Saturday after RSV days as VDO. A 3 day starting Thursday comes up while on long call on Wednesday. You could be assigned that trip (if you are only one available) without your consent and you will only get VDO pay for Saturday. (Obviously this would have to be a legal assignment and 30/168 would have to be met.)

Been there, done both scenarios. I recommend putting VDOs only before RSV days and leave a HDO after RSV blocks until after you are released from your last day of RSV.