Tempo is easy enough that you can do as long an interval as you like. 5-10-20 minutes shouldn’t be a problem.
I hit my best numbers ever the year before with a tempo build - a lot of 3x20minute sessions and some 4x20s. One could also string together a lot of 5 minute intervals with 1 minute rests if you wanted. I don’t think it matters how one gets to the endpoint. Just keep increasing time in zone and keep fatigue in check.