Are 150m repeats good for 800/mile race prediction?

I think 3x400 is a good predictor workout, that's a solid workout though

I'd put you relatively close to your PRs, probably a little slower.

It's a lot better of a prediction of your 800 meter potential. If you ran 4:53 pace try for a 2:27 800.

No it is not.

O.P., you did an easier version of 6 x 300m. Many 800m athletes do 9 x 300m at 800m race pace. Just know an 800m race will hurt more than discomfort in said workout.

Good workout, yes

Predictor, no. But I’ll add the caveat that if other sessions are going well, then you might be in shape to PR by quite a bit.

Other sessions that would pair perfectly.

6x3 min fast, 2 min float.

4 x 1000 full recovery.

Go through those sessions without dying by the end, and you should have enough juice to hold onto that pace from the 150 workout.