level 1 - 4 seem like a waste if one was going to get to this level on purpose.
level 1 - 4 seems very common for mushrooms but last a lot longer on mushrooms.
Thats why only level 5 seems like the goal when one is going to experiance.

DMT

Level one 10-15mg slight cev's no oev's. sound manipulation. Light body load.

Level two 15-25mg breakthrough for some. STRONG cevs and possibly same for oevs. Med to strong body load. Carrier wave present.

Level three 25mg+ should be breakthrough if properly vaped. Very clear visuals, usually opening of eyes does nothing. Body load so strong you probably won't feel your body.

Basically.

i don't think any of them are a waste! certainly 5 is the endgoal but i do enjoy a little DMT buzz every now and then. usually in the 3rd level though. 1-2 if i'm clearing residue

Here, here. Yes breakthrough is the goal with DMT. It's what it's all about, right, and more easily achieved through smoalking than any other substance/ROA I'm familiar with.

That said, last summer I experimented quite a bit with close to threshold and sub-breakthrough doses and that seemed to me to open up more avenues for research into its application for purposes more related to physical health and for treating depression.

It's a useful tool for many applications. I grok what you're saying though about perceiving sub breakthrough doses as being wastes of time and used to feel the same. But for the reasons above and sometimes a mild half hour trip is a nice way to break up my day.