Do I need to provide proof of a cooking class every six months when entering Thailand on a soft power visa?

Or simply do what you have committed to do for the five years and respect it..so if that's cooking why not learn!

When applying for the DTV under the "soft power" category, like Thai cooking classes, you initially need proof of enrollment. Upon entry, you don't need to show this again for the first 180 days, but for extensions, having updated proof of your continued participation might be wise- some post in this group has experience already having their DTV extension. However, discretion lies with immigration officers, so keeping documentation handy is advisable. 🙏

You have to cook for the immigration officer

There are no reports that people entering the country are being asked to show that they're still enrolled in the activity you signed up for when you applied for the DTV.

Now the same cannot be said for people trying to get a 180 day extension on a soft power DTV at the immigration office. You have to show you're still enrolled in what ever it is you got the visa for to get the extension

So I'd say as long as you bounce in and out every 6 months rather than try to get the one in country extension per entry you can apply for you should be fine..

At this time passport control is not asking anything from people when they stamp in other than the PDF print out of the DTV and your passport

No they don't, only to extend in country. If they do start checking you can use a visa agent to do a border run and get a new 180 day stamp no questions asked.