Yo @masulum, welcome to the slots addict club! I believe this is the first time you post here.
May i know, Would you prefer to buy free spins than increase normal bet to get chance the free spins feature? if we use additional bets to increase the chance of getting free spins, this is also have small chance. because I didn't have a balance, so I tried it on the demo, several times I waited quite a long, and it ended losing more money than buying free spins.
It depends mate, if I play with USD, meaning $0.2 - $0.25 minimum bet (let's say for Starlight), I will do normal spins because buy free spins cost $20, which will rekt your balance pretty quick.
If I play with IDR, meaning dirt cheap IDR 200 minimum bet, I will do bonus buy because it will cost only IDR 20k
That's the power of bigger balance in slots game. I'd do IDR 60k bonus buy, and increase it to maximum IDR 100k. Keep in mind, this is my way of getting maximum entertainment out of slots game, not to get crazy sensational win.
Try at least 15 x IDR 20k = IDR 300K budget and keep buying IDR 20k bonus. You should notice it will last quite long, and the chance of being busted is pretty slim as long as you don't try to get a huge profit. If you tired/bored already, just keep the balance (or withdraw) and use it another day.
If you want to play normal spin, deposit at least $50 and find games that have $0.1 minimum bet. 500 spins should have a pretty good chance to trigger the bonus round, and it will last quite long if you don't use fast/turbo spins. Yes, you can still play normal spins with IDR, but it will only waste your time.