Adjustment necessary for stationary trainer I am looking at purchasing a stationary trainer that will be shared with my wife and would prefer to do a wheel off trainer.  

Both of our bikes have a 11-28T cassette.

So, theoretically, if the wheel of trainer has the same cassette the derailleurs will not require adjustment.   Is my thinking correct?

One of the bike maintenance things I have not mastered is derailleur adjustment.
First, the bikes and the trainer need to have same number of cogs.

The adjustment depends on cassette location on the axle, not the cassette. With any luck you should be able to switch to different wheels and trainer without adjustment, but this is not guaranteed.