VO2max Short/Short vs Short/Shorter

Hi,
3 questions i hope people can answer what they think.

  1. What is your main VO2max (tabata) workout and why.

  2. Would it be best to do 1:1 for base/build and save 2:1 for speciality and taper for form?. 20 Min of work time is enough for 2:1, do you need 25min for the 1:1 to be equal? (keep in mind increased rest gives increased avg watt on the intervals)

  3. I find that 30/15 on my neo on ERG is hard to get same quality as a bit longer intervals. Is it because my power profile leans to the right or is it because it requires extra power every time u go from 40 to 130%.

I’m fond of bluebells type at highest possible power and 1:1.