RidwarePhil said:...5 min L3
5 min L4
5 min L5
(repeat x 3)
Warm down
What is this targetting? ...
Well the first two (L3,L4) aren't targeting much of anything. If you string them together to make a 10 minute L3-L4 block then they'd marginally be targeting SST at the very short end of the useful duration. The L5 work is fine, but following the other two it's unlikely you can give it your best effort.
Personally I think it's good that that came from you exccoach. It's a muddled routine to follow day after day that doesn't really focus on anything and tries to do everything.
You're right that by definition you won't be able to do a 15 minute L5 block although you could do a few shorter say 3 to 4 minute efforts with equal rest in that block.
I'd strongly suggest rearranging your main training days to follow a decreasing intensity - increasing duration approach. Something like:
Day 1: L5 repeats, 3 to 5 minute efforts with equal rest shooting for 25 to 30 minutes in level. WU, CD, nothing else, total time ~1-1.5 hours
Day 2: L4 repeats, 15 to 25 minute efforts at ~95% FTP, WU, CD, 5 minutes between efforts, total time 1.5 to 2 hours
Day 3: L3 ride, 30 minutes to 1.5 hours in level steady effort or 30 + minute blocks. WU, CD, 2+ hours total
The idea is to hit your hardest effort early in the multiday block when you are well rested. The key is to keep the total duration short enough so you still have juice for the next day which is easier but longer. The block finishes with the most enjoyable and longest workout. Take a rest day before and after the block and either repeat for a sliding schedule or do a two day weekend block (L4, L3,L2+) to stay on a weekly calendar based schedule.
If your longest L4 and L3 efforts have been 5 minutes to date you'll probably need to work up to the longer repeats. But you really have to spend at least 10 minutes at those levels to get any training benefit so try to start your longer L3 and above efforts with at least 10 minute blocks. If that feels too tough then start with SST instead of pure L4 efforts by working at approximately 85% of FTP until that starts feeling easy for the longer repeats.
Good luck,
Dave