Not sure what you are saying about the odds, but not all those multiple outcomes have equal liklihood but. I have seen literally hundreds of 300 games over the past 25 years, and maybe 10 or 15 all spare games. I can only think of one I have had, against more than 40 300s. By the way, I am consudered a very good spare shooter

Bottom line, the odds against leaving 10 makeable spares without throwing a strike are pretty high. The odds against throwing 12 strikes in a row is very high also, but probably a factor of ten higher against the all spare game. Totally different if you are trying it certainly changes the odds. I have bowled for almost 60 years. I cant remember ever putting 10 balls in the pocket without getting a strike.