When you raise your own heifers, and they come from a top AI sire or really good herd bull, then you have a pretty good idea of what you are working with. I agree that it takes a long time to get that going, but buying replacement heifers is a very expensive part of the cattle business.
One option for those that are able to do it, is to use sexed semen. We use SAV Raindance sexed semen frequently. It's good stuff, I assure you. Anyway, if you have 20-30 cows/heifers and you AI them all to Raindance and assuming you successfully get them settled and calved out, then you essentially have replaced all your females in one breeding cycle. We have done this, and it works.
I had an old farmer out on the place a year ago and I told him about sexed semen, and his face curled up. I told him "I'm going to take those 20 heifers you see right there and produce 20 more females with them in one season" He told me "that can't be done, I don't believe it" Well I have almost pulled it off, and have invited him to come back and see the results.
By doing that, there are suddenly in a short amount of time roughly 40 females. do it one more time, breed the 20 original females again to SAV Raindance, and then breed the 20 new females to say a Connealy bull that is sexed from ST Genetics and in a few short years you have almost 70-80 females barring any big disasters, and assuming you are HIGHLY DISCIPLINED in not using a clean up bull. They are all young, high quality, and you obtained them for a fraction, a tiny fraction of the cost of buying them. However there is one VERY BIG problem with this idea, most people think 3-4 years is an eternity and they will not stick to doing this. Like I said, there is some discipline involved.