Depends on how temperamental you are to changes and how versatile an archer you are.
For me it fits in well with the other practice I do: sitting shots, obstacle shots, reverse carts, leaning, moving targets, threading through blowouts, uphill down hill, whacking dirt clods and grass clumps, shooting at unknown ranges, etc.
Seems like a good skill to have to be able to pick up a new bow and be able to hit with it sufficiently after an afternoon. Hill mentioned that a proficient archer should be capable of doing so readily.
Suppose you whack the limb of your longbow on a tree trunk mid season during a hunting shot and break it off at the nock? What are you going to do now? Pick up the other bow, obviously. You definitely need to be somewhat familiar with it.
And to me, the more shooting you do at the more different kinds of targets, with ANY bow, the better.
But, beware the man with only one bow, he probably knows how to use it...