For situations where large (or infinite) tuning size is not a problem, such as in the use of electronic instruments, a regular tuning is a good choice. If tuning size is a problem (such as in the use of acoustic instruments), but the piece avoids wolf intervals by visiting only small range of pitch classes (usually 12), a truncated tuning is a good choice. If tuning size is a problem and the piece visits a large range of pitch classes, a well temperament is a good choice. Historical factors may influence these decisions as well: it may be desirable to render a piece in the tuning that the composer intended it for. In addition, irregular temperaments might be employed to create subtle effects of key coloration.
Still, in general, for electronic instruments, regular tunings seem like the best we can do as far as our goal of just M3 and P5. Nonetheless, it is natural to wonder if we can somehow do better, perhaps by allowing dynamic intonation, multiple tunings of the same pitch depending on context. This might allow just M3 and P5 to be simultaneously possible. This idea will be the subject of the next section.