A 2001 genetic marker study of tetraploid roses found that of 115 open pollinated seedlings, only 52 were self pollinations
That’s good to know, Henry!
I also imagine that it might be a case by case basis since every cultivar or species has variable patterns depending on the time of the season. For instance, I would assume that Playboy or Rosa californica will have more non-self OP’s than would Rose Rhapsody (too many petals during spring) or Rosa primula (nothing else likely blooming) would.
w.r.t. Henrys findings in:
http://home.neo.rr.com/kuska/how_many_days_should_one_pollina.htm
I wounder what the results would be from pollinating 2 times. Once on day 1 and then again 4 or 5 days later.