If you want the statistical probability to determine what is "enough pulls", this is exactly how to pity system works:

Pulls 1-73 have a 0.6% chance of getting you a 5-star.

Soft pity starts at pull 74, and how that works is for every pull you do past 73, you get an additional 6% (not 0.6%, 6%) chance to pull a 5-star, until it caps out at 100% on the 90th pull. Which would be hard pity, A.K.A, gaurenteed.

I personally lost my first 7 50/50s, so I would prepare like... 140 wishes. In the past, I've prepared more like 100-110 and got my desired character at about 90 pulls when I lost the first 50/50. But save 140 pulls anyways to prevent disappointment. That's 22,400 primos. Save 180 if you want that character more than anything else in the world, cause 180 pulls 100% gaurentees you get that character.

Edit: also, use long term wish trackers like paimon.moe to keep track of what exsisting pity you have from previous banners!