Hi - I’m doing some rewiring and got to thinking about this. Latest NEC code requires all junction boxes (JBs) to have a neutral in them, but does not require a live. In the case of a two way switch you’ll have both neutral and live in your JB by default. But for a 3 way switch you’re likely to end up without live in one of the JBs. Can smart switches deal with this? To be clear - one of the travelers for the 3 way/4 way would always be hot - but it would toggle between when is hot and which isn’t as the switch gets toggled.

Thank you!