This is my realistic targets with betta's
1st spawning, expect the male to eat free swimming fry. if 5-10 fry get passed that you got a good male.
2-3rd spawning, should be much better with fry and 10-30 fry.
After this point if he's a good male you may get 100 plus from each spawning.
(This is fry only only expect 5 or so fry to get to adult size, if you do that then your doing very well)
Fry success is also due to the owners experance of feeding fry, you lurn as well what the fry want and how much to add. Feed to much and not do water changes and your only have dead fry.
The next dodge point is a 2-3 weeks old the fry start to breath air, if this cooler than the water, or dry this will also kill the fry, so it may take you longer to lurn how to rear the fry then anything else, so by 5th time I would be be happy with getting 30 fish to adult size, and in around 3-5 months.
So basically
Novice breeder (owner not fish) - After 4-5 time you should now know what your doing and getting 30+ fry to adult.
Novice fish - first3 spawning's dont expect much unless you got a great male