Hi, and welcome to the forum.
Bettas will practically breed in any amount of water. But can we (the breeder) risk the chance of losing the female? You need to know your bettas before you try the Thai way.
Veteran females usually spawn faster than first timers. If you release her in the late afternoon, she will spawn the following day.
Specially for new breeders; if you don't know how much to feed your batch of fry, it's best to breed the common way. If you feed too much, very little amount of water will need more wc. Further with all that fry, it would be difficult to siphon water out without sucking some fry.