In my experience with most trees... When the sunlight hits the trunk, you get new growth... unfortunately, the growth is not the attractive layers that the original branches were... but instead tends to be "suckers" or "water sprouts"... Usually kept trimmed off because the desired shade is gone with little likelihood of getting it back.
Of course, you could always use the limb spreaders employed with fruit trees...
https://www.starkbros.com/grow...
I don't think I'd be notching a valued tree...
