Well, there will be 2 reasons to expunge a record:

The first is because you were legally entitled to a pre-trial intervention or you got a bad public defender who should have successfully gotten the case(s) thrown-out or at least reduced in charges. This is essentially a re-consideration of your cases.

The second, less likely, reason would be based on an evaluation of your progress and rehabilitation. A testament to your character.

If you're out of state, the judge would have less motivation to take-up any review or attestation of character. If you get busted for drugs again, since you're in another state, you wouldn't be brought before him again. Essentially he would just be wiping your record clean so you can go cause trouble in another state. He has no motivation to do that in it would look really bad for him if you got busted again in another state.

The other reason is that you would have to make multiple inter-state trips since each of these cases would be dealt with separately.

I think a judge is going to look at your cases and see a pattern and say "nope. you had multiple chances to turn-over a new leaf and failed to do so. The punishment stands." And to be honest, that's exactly what he should do.