I know CTS loves those shorter intervals, but I'd STRONGLY recommend doing your focused SST/L4 intervals in longer sustained efforts with 10 minutes being the bare minimum and personally I wouldn't block out L4 efforts that were less than 12 minutes each. It takes nearly 8 minutes to exhaust higher end systems so if you really want to focus on sustained metabolic power (which is the essence of FTP work) then the first 8 minutes is basically just priming the pump and getting the effort started. Stretch them longer even if the power needs to drop a bit to pull that off.
I know that's counter to what the CTS book tells you, but having done a lot of these over the years and having worked with quite a few athletes working these efforts it's really clear that longer sustained efforts are far more productive but they do take additional mental energy as 20 minutes or more can seem like a long time to stay focused when riding nowhere on the trainer. Again personally I find it mentally easier to do a solid 45 minutes and even a full hour at 90+% than it is to rally for that second or third 20 minute effort but YMMV.
And I'd also strongly recommend working up to that fifth day each week but it's fine to keep that day easier and shorter. Try to fill that extra day with a 'soft SST' day where you roll for perhaps 40 minutes at around 70-80% of your current FTP. That's not a brutal workout either in terms of intensity or overall workload and a lot of folks find these moderate and not terribly long workouts great for freshening up the legs but mostly it helps in terms of training frequency or how often you get on the bike to at least do something each week. It's not total rest but you'll tend to be pretty fresh the day after a workout like this and ready to get back to more focused work.
Good luck,
-Dave
I know that's counter to what the CTS book tells you, but having done a lot of these over the years and having worked with quite a few athletes working these efforts it's really clear that longer sustained efforts are far more productive but they do take additional mental energy as 20 minutes or more can seem like a long time to stay focused when riding nowhere on the trainer. Again personally I find it mentally easier to do a solid 45 minutes and even a full hour at 90+% than it is to rally for that second or third 20 minute effort but YMMV.
And I'd also strongly recommend working up to that fifth day each week but it's fine to keep that day easier and shorter. Try to fill that extra day with a 'soft SST' day where you roll for perhaps 40 minutes at around 70-80% of your current FTP. That's not a brutal workout either in terms of intensity or overall workload and a lot of folks find these moderate and not terribly long workouts great for freshening up the legs but mostly it helps in terms of training frequency or how often you get on the bike to at least do something each week. It's not total rest but you'll tend to be pretty fresh the day after a workout like this and ready to get back to more focused work.
Good luck,
-Dave