Is there a maximum visit period to Singapore ? I need your advice :(

Can you tell us the specific reason for visiting too often? Site seeing is not a smart answer in a tiny country like Singapore. This could be the exact question immigration officer may ask.

If you have transit via Singapore then there shouldn’t be a gap of 24hrs at worst case. So, 7 days GAP is purely intentional.

About ban or denying to enter Singapore, yes there could be possibility. I would suggest better avoid it. You are lucky enough to visited 3 times in few months and didn’t encounter immigration officer call to their office to ask purpose of your so frequent visit. Good luck

It was purely 100% for holiday , I just finished my study in Singapore 3 months ago and I got 3 month left waiting for my school result which will come out in January therefore in this past 2 month I just went there to travelling around and have some nostalgia , meet old friends have fun etc

and for the transit part , I think I say it wrongly.

I just want to have a short stay in Singapore for 7 days to take my exam result and travelling around Singapore for the last time as I will not be able to go to Singapore again as I will study in the country that I will visit after Singapore for 4 years.

The average tourist visits Singapore for 3.5 days.
You need a good reason for staying much longer!
I think (without warranty!) that you will get the 7 days after some questioning and after showing them your onward ticked, school enrollment at the onward destination - and prof of your acommodation in Singapore. But don't try this again!