There are many factors that will determine whether Tangs get along. Relative size of the fish, similar versus dissimilar species, order of introduction, amount of space they have to swim around ..... so while the OP may think tank size is irrelevant, it is not. All other things being equal, more space means more harmony.
Now, you can certainly keep fish in tanks that are smaller when they are small, but eventually there will be problems. For example, I have a Naso tang in my 90 gallon 'grow out' tank simply because it got the stuffing beaten out of it in my 265 (principally by the YT). Once it puts on some size, it's going back in .....