Hi there,
trauma therapist in training here. I am aware of the theories about the default mode network, enhancing neuroplasticity etc. Personally, I think that these models don't hold much explanatory value as of yet. Don't get me wrong, I'm not saying they are incorrect but I think they neglect the psychedelic experience itself as the core of what happens when we take psychedelics. I'd rather look at it from a psychological perspective and realise that these experiences can be highly introspective, thought-provoking & can induce behavioural change sometimes, which can help people on their healing journey when integrated correctly. I don't think that simply smoking DMT every two to four weeks at home by yourself will significantly change brain chemistry in a way that would heal somebody if that's all that person did. It's just not what I see happening in the average person.
To me, a healthy brain is a bit like healthy teeth. You need to take care of your teeth every day at home & you go to a dentist once or twice a year to check everything and fix anything that might have happened. I understand psychedelics as some sort of dentist's visits, not as brushing the teeth.