Yeah, I felt the same way haha. I finally felt confident enough to make these changes after working on some smaller scale areas.

I see what you're saying about mapping them separately, I actually went through the same line of thought as you and went back and forth between the idea of separating podiums from their towers.

I think neither what I did here or the alternative you've suggested is the right way going forward, and I'll explain below.

I think it's much better to have one way to represent the whole building, and parts to represent distinct portions. In general, towers and podiums should be mapped as building parts as part of a single building footprint. This is because the podium and tower portions of buildings usually have distinct internal layouts and typically have different building materials and architectural design/visual look.

Having two separate building ways define the same structure is bad data to have in OSM. Splitting towers from podiums as separate buildings would imply that the podium structure is comprised of two adjacent buildings, which is usually isn't the case in real life.

Mapping them as separate building parts as I've done here has the exact same problem, as it implies that the podium portion of the tower area is a separate unit than the rest of the podium.

This would be problematic when we have retail usage at the podium level, since separating the parts into two buildings would imply that the retail area is located within two distinct buildings, instead of one comprehensive shopping structure.

How I think I should have mapped the Brentwood towers is having the entire podium footprint mapped as a building part, and then the tower portion mapped as a building part on top of it with the building:min_level= tag starting at the first floor above the podium.

The Marine Gateway development (https://www.openstreetmap.org/way/360225154) is a good example of what I'm talking about here. If the office tower above the cineplex was mapped as a separate structure, the supposed "building" would have cut straight through the cineplex, Winners and T&T supermarket.

I think a good way to think about it is to imagine walking through the building. If there is a corridor that ends up crossing two mapped buildings, then maybe they shouldn't be separate.

So at the end of the day, I think that the guidelines in the wiki actually have it right. We should be using building parts, just not quite the way I've done it here.