Late extract addition question

I'm a partial masher, and I always utilize the late extract addition method when brewing. Last night at my HB club meeting, after it went through my ingredients and methods for my Oatmeal Stout, one of the members cautioned me on the late addition method. He stated that I should boil all the extract for the full 60min to be sure all the DMS is driven off from it as well as any grain mashed. I have never seen this brought up on the board before so I guess I'm just looking for some insight/opinion from you all. Thanks!

I've never heard of or noticed DMS being a problem with extract. My understanding is that has already been taken care of during the extract manufacturing process.

My understanding was that DMS compounds are produced constantly
in the wort at temperatures above ~80F. I'm not sure if this is a limited
process or a continual process, however some people caution about
cooling with a lid on. In that case, it would seem that DMS would be
produced even after the boil.

Not sure though.

I have read that DMS is taken care of during the production of extract also. Although more can be created, it seems that you would be okay if you put the extract into already boiling wort and brought it back to a boil for a few mins.

I've done about 30 PM batches and didn't boil the extract for 60 minutes on any of them. Never any hint of DMS, I don't think there's anything to worry about.

DMS is produced during boiling, so you only need to get rid of it while you're boiling. As you cool, it stops being produced. Check out the DMS paragraphs in How to Brew - By John Palmer - Common Off-Flavors