You can eat up to 20 quail eggs per day but you likely even wouldn't want to eat 20 quail eggs per day because you'd likely get sick of eating the quail eggs or any eggs at 20 per day.
I eat as much as 5 quail eggs everyday in the morning and along with my lunch and that's more than enough quail eggs for me.
Eating more than 5 quail eggs may make your stomach hurt although you can safely eat 20 quail eggs per day but you would likely not get to that point.
Quail eggs are a bit more expensive than chicken eggs so you might not be able to afford to eat 20 quail eggs per day anyway.