The ability to import schedules in FIT files is on my to-do list but at the moment I am focussed on the navigation improvements.
A couple of years ago I coded up the ability to import schedules that the app currently supports, but I asked around (including on these forums) and most people said it wasn't worth including unless it allowed nested repeats. That would have meant improving the current schedule functionality rather than just allowing intervals with the current functionality to be imported, so I put it back on the to-do list.
Since then Apple have released intervals without nesting, so I have been tempted to enable that code again, but at the moment I am focussed on navigation improvements. Sorry about that.
Being able to support the level of intervals that Apple have would be awesome.
My own use case for intervals is to have my plans in intervals.icu & use Watchletic to sync them to the Watch where todays Workout is then immediately available (and future from my calendar are a click away) in the native Workout app.
If WoD could have a vaguely similar workflow (even via a manual download of the FIT from intervals.icu), I'd probably then use WoD for my Interval workouts, as SOMETIMES I also need a map.
Currently I run "Map Only" on WOD whilst doing Intervals where I need a map, and only 'properly' use WoD for the non-structured runs where I happen to need a map.
(even though its perfectly simple to create the structured workouts in WoD, its just not as simple as me dragging a plan into a calendar and having the next 16 weeks set up for me and then not worrying about building any interval sessions on the watch or phone at all!)