I've seen a study on DAA, where it raised test levels some for the first 12 days, but then levels quickly dropped back to starting point. And I've seen another study, where DAA actually lowered test levels. I don't recall of what magnitude the drop was. I've seen bro-speculation of DAA being beneficial for men with low test levels, but not useful or possibly even counterproductive for men with high/ok test levels. So by that hypothesis, it could be beneficial on pct, but that's just some speculation I've seen and anyway it would be a drop in a bucket with serms in the picture.
Osta is suppressive, so it does not make sense to include it in pct. Maybe the ones who think it does, still believe in the "sarms are not suppressive" BS. Or they think, that the serm(s) will over power the Osta's suppressive effect and can benefit from the mild anabolism, while the serm will still pull test levels back up. Anyway, it's suppressive, so it's counterproductive to hormonal recovery.
I've ever only used Tamox, but I see the possible benefit of having both Clomid and Nolva. So no experience on stacking serms, but I'd probably do 25 C and 20 N, if stacking those two.