My BTO has been paid off. Should I regularly transfer my cpf OA to SA if I don't intend to buy another house?

Based on your age and achievements so far, I presume that you are having the max cpf contribution already Or have enough cash to pay off your bto early.

if you do regular transfer from OA to SA, and with OA getting the Medisave component since you have already hit BHS, then you would be hitting your FRS on your SA pretty soon if you have not reached it by now. In that sense, it may not be necessary for you to do the transfer but I may suggest instead for you to do a cash topup of 7k yearly to the SA to take advantage of the additional assessible income tax rebate for voluntary cash TOP ups. That will help you in your tax savings and you get to enjoy the compounded interest of 4% for your cash topups too.

once you have hit frs in your SA, you will not be able to do anymore top ups anymore and will not enjoy further tax rebates later on. So I would say you don’t need to rush into OA-SA transfer now if your cash flows are ok.

If you are confident that you might not be buying a new home, you will be better off to transfer your OA to SA to maximize your yield.
However, you have to be certain about it because transferring your funds to SA is a one way ticket.
Or if you would like to, you might want to do periodic transfer of your OA to SA in case you have a change in mind with regards to purchasing a new property.

Congrats OP on paying off your BTO.
What you can consider doing to is return the CPF monies used for paying your BTO, as this sum would have interest accured. In other words, you will own yourself interest on the amount you used for paying off your CPF. Do note that thus amount can only be paid using cash. See more details here: https://www.cpf.gov.sg/Assets/members/Documents...

Transfer of CPF OA to SA would be advisable only if you do not need to touch the funds as the process is irrversible. Do note that your CPF OA can be used to pay for your child's education fees too, while SA is only meant for retirement.

Congrats on paying off your BTO! CPF-OA can be used for the following expenses which you should consider before transferring money to SA. The transfer is one way and you can only get money back after 55yo, assuming you reach the full retirement sum by then.

1) children’s education - know how old your children are now and if you intend to use CPF-OA for their tertiary education should they intend to study in Singapore.

2) yes you have no intention to get another flat/ house, but would you change your mind 10 years down the road (understand from the comments you are currently 35), when many couples get their second house around 45yo for the sake of having a second property to receive recurrent income

3) know your risk appettie - you are currently 35 and there’s still 20 years before reaching 55years old. It’s good time to start investment, especially when the government just announced slashing sales charges for CPF investments to 0 sales charge. However, 0 sales charge isn’t equal to no charges, admin fees are still involved when you invest, and unit trusts have continuing investment charges. You can also put your money in shares and gold certs (via UOB) if you feel you are up for higher risks. Leaving money in OA is good for 2.5%p.a. interest, and SA is good for 4%p.a. interest.
Investment outside of CPF is non capital guaranteed, though the returns can be as high as 4% to 10%p.a. By Singapore Law CPF have to give these interest rates. So the risk for leaving money in CPF is when the law changes.

Just a personal opinion, since you’re still young, you should explore investments. It’s not recommended when you are close to retirement.