Questioned after multiple stamps in/out. What next?

Hi,
Im British &been in Thailand for 10 months (5 x 2months stamps) doing 1 day trips to Singapore.
I got questioned about the length of my stay at Don Muang, but i was let in without much fuss.
Something was mentioned about getting a visa next time (though i prefer a short trip to visit Singapore againvs Multiple days in Cambodia).
I wasnt sure if the immigration officerwas giving advice (on how to avoid potential issues withfuture immigration at entry).
Or have Ibeen registered intotheir system and surely denied entry again without visa?
Also, if i need to get a Visa next time and in some system. Does that mean i need one everytime going forward? Or i can get a visa once and then do more exempt entries until they tell me to get another visa.
Im a young guy (marriage, retirement arnt an option) with plenty of cash savings. I just dont want the hassle and wasted time of getting Tourist visa in places i dont enjoyvisiting.