Boil or simmer what?
I assume you’re referring to MHRB? Powdered, shredded, or whole?
If you’re extracting DMT from powdered MHRB, you don’t need to boil at all. Just let the powder steep in hot water (acidified with vinegar) for as long as it takes the powder to settle, decant the liquid, and repeat 3-4 times. Reduce the resultant liquid to a manageable volume with vigorous boiling, basify, and extract with a NP solvent. You’ll get yields as high as you would if you boiled for hours.
Of course, if you’re using coarsely shredded bark, you’d have to boil for a very long time to get all of the DMT out. But with powdered, no boiling is required.