If you buy one or two seedlings of a cross, odds are that you will end up with an average clone for the cross. Buy a flask (or a bunch of seedlings) and bloom 6 from the same cross - and you are pretty much are guaranteed (say 80% + chance) to have at least one bloom with a significantly better flower than the average. If you are in the game of trying to get awards, bloom 10 or more per cross. The pro's selecting breeders for the next generation may set aside a hundred or two and select the best from that bunch. It is the compromise between the amount of room you have, the time you have and whether or not you like the cross well enough to want to keep watering that many seedlings for that many years. I try to bloom a flask's worth of a few crosses, I also will occasionally spring the extra cash to buy an awarded plant so I don't have to grow 100's to get one good one. Which tactic I use depends on how much room I have at the time.