Can I use cumulative deposits for the 65k monthly requirement for visa renewal in Thailand?

Paet of the trick is to make it clear and obvious for Immigration, so I'd wait until your final monthly payment is in place and have one single standing order to capture the full amount then

I deposit the required amount during each calendar month but with no pattern at all in terms of amounts or number of transfers.

On request KBank give me a 12 month printout showing all the international transfers into my account.

This has always been acceptable to Chiang Mai Immigration.

I receive 2 4-weekly pension payments directly onto my Thai bank account. The second comes in about a week after the first. This has never been a problem with immigration when extending my visa.

Immigration did, however, raise an eyebrow when I had to arrange a third transfer of few extra baht after Liz Truss crashed Sterling 2 years ago, but I got away with it as it was only for a couple of months.

Suggest you KEEP IT SIMPLE...

Do your monthly transfer of 65,000 Thai baht or more in a lump sum.

While it may be possible for several monthly deposits, your Thai Immigration office may not be happy with the added work in seeing you meet the deposit requirements, but your Thai bank may not be able to prepare the needed verification letter you obtain from them to submit with your application for the one year extension of stay as retired.

Question : are you ALREADY on a one Year extension based on retirement? Or are you planning to apply for it inside Thailand?

What is your passport nation?

I guess it’s down to the interpretation of your local immigration office.

They can be different dates along as it totals minimum a month minimum. You may want to send it all from one account for less transaction fees