I not sure if everyone regret just a day or two because someone who has a healthy mindset after regret a mistake at gambling he will not come back and stay away from gambling.
If someone is like that, that's a normal thing for a gambler to experience. Regrets are always at the end of the action that we do and if it's with gambling, whenever we lose a little or a lot of money, we're there to just admit the mistake and then will call it a regret and will think of something better. It doesn't matter how long has been one able to regret his actions, be it one or two days after he has gambled as long as it's the end of his gambling activity then that should be still enough to say as a regret because it's at the end of it.
While feeling regret once we have lost more money than what we wanted during a particular session is a good sign, it is important that actions are taken based on that regret, as there are a lot of people out there which regret what they did but when presented with the opportunity they do the very same thing they regret anyway, and in that case regret is useless, gamblers need to use those feelings so something like that never happens to them again, otherwise it is pointless to feel that way.
I agree with what you said if you make the same mistake several times and experience a loss it's not a feeling of regret it's just like a lost dinner.
Many of us have experienced or even still do that because naturally this is a problem with risking money which then losing the feeling of losing this money triggers our minds to become unstable and think of chasing losses which always deposit money to chase defeat even though the first defeat feels regret but all that means nothing.
There are no regrets in gambling for me because if it was really a gambler who regretted they would leave gambling and would never touch the gambling table at any time but it turns out that most of us still come back to gamble even though it's been 1 year and that's not regret for me