Wow - well done in doing that on the road!
Yes, I find short, sharp efforts are much easier (and safer!) on the turbo. OTOH I find it far easier to do intervals over 10 minutes outside. What I would really love would be a long hill with a smooth surface and gentle, steady gradient for doing intervals. I've not found one within an hour's ride of here. The road through Epping Forest is good, but busy, and a few roads up the dip slope of the Chiltern Ridge
As my chest infection is abating, I tried VO2 max intervals this morning. But I couldn't keep the power on and had to dial it back by 15%, essentially down to threshold, in order to complete the session, so probably not so much benefit from it. Will tweak my programme to take out the VO2 max stuff for the next week and put in sweet spot instead.