It depends on how many males and overaggressive females you get in a spawn.
If you aren't willing or capable of culling a spawn, you really need to rethink trying to breed bettas. I have a halfmoon x crowntail spawn right now, they are a week old. I'll be culling any that show deformities or bent spines, and ones that show the least desirable characteristics. For my goals, that means fish with wildly uneven fins, messy crowntails, crowntails with uneven ray extension, or tails with narrow spreads. Fish that show the best characteristics will be kept for future breeding, and the inbetweens will be offered for sale.
I knew before deciding to do this that I would be required to cull back the spawn. If they were mammals, they would just get sterilised, but that isn't possible with fish, and because of the high potential for suffering these particular fish face, I'd rather cull the undesirables and sell the better ones that would make good pets.
Eventually, I want good crowntails with good coloring, even fins, good ray extension, etc. I've never had a crowntail before because I've never been happy with the ones I've seen for various reasons. So my goal is to make good crowntails with halfmoon spread, even fins, and strong rays.
If you don't have a goal and just want to breed because you want to, it can be much more difficult to make anything back on the spawn. Add in the cost of the live foods you need, keeping the parents in good health, the extra equipment such as airline tubing, filter, aerator, eyedropper and/or baster for spotcleaning the tank, live plants, fake plants, plus the extra water conditioner you'll be using because you'll eventually be doing daily 50-80% water changes, it's going to take a while before you earn back on what you invested in your fish.
I have fish stuff all over my room, I slept with a lamp on for four nights so my male could easily see his eggs and fry to keep them in the nest. It takes roughly 2 hours to do a water change on the fry tank and it's not even 2.5 gallons I'm removing and adding back. The first few days, I fed every few hours, and now I feed three times a day, and feed my male twice (he's still with his spawn). Not to mention the two 15 gallon tanks I have for my other two males and my sorority.
My spawn is only a week old and it's been a heck of a lot of work so far!
If you decide to breed, you need to think long and hard on your end goals and how you're going to accomplish everything you need to do to get healthy fish. I'm starting with petstore fish but I look at aquabid every single day, looking for quality fish I could potentially use to improve what I'm going to be working on. One of those fish is going to cost me around 60 bucks or more because of the cost of the fish itself and the shipping to get it to me.
I first researched breeding when I was a teenager, and I had fish again for four months before I decided, but I spent a lot of time thinking about it beforehand. You need to make sure you can do right by your animals before you jump in.