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I can't stand turbos, but I'm weak enough that I can just about do vo2max on rollers, I find that beyond 400W the cadence becomes too hard to stay on top of but I'm never there for long.
I tried to follow plans over the winter but found it too hard with uni/family/work commitments so have recently switched to doing two tough vo2max sessions in the week then a long ride at the weekend with as much climbing as possible. There are lots of different sessions you can try to mix it up, I just try to mimic what I'll be doing on the road and 3 weeks of it seemed to add about 25W to my (meagre) FTP.
I'm sure there's some advice about if you can't maintain within 5% of the power of your first interval then you should stop. I'm sure I've read loads about short intervals like that being about 'quality', and if you're not hitting your target then sack it off.
Recently I've been doing a day of 4x6, 5x4 or something, often with the first minute/30 seconds at >150%, then the rest at >115%, and a day of 1 minute on/off full gas, repeating until collapse. These are specific to me though as I want to improve at climbs near me (North Yorkshire) which tend to be short and steep.
Perhaps try doing 3 sets of 4x4 or something, with a decent rest between? If you're too fucked to do the intervals then there's no point (I believe I read somewhere).