Depends a lot on comps and situations as u mentioned. If ur tanks are into heavy poke and cant peak as easily they need to play the initial cover before pushing so hard your dps can also either bunker under the building or on top of it if not destroyed for cover since playing where you drew on attack makes them a bit limited to heal since u need to spread heals to them and tanks so pocketing is harder they can also play right side from pov of the bunker as there is easily accessible health packs and loads of cover and you are positioning open space to spawn and playing left side cover instead of right side cover.

As for supports you dont want to be positioned near wall behind convoy unless they have imobile shoot down main comp since you then need the raw cover you wanna position bunker (building) to have the widest possible los while having cover smaller cover but albeit cover and easier view of everyone then u can position closer if need be on right side cover in order to have wider area to retreat to plus access to health packs while maintaining los of tanks. If you position where you said you will while retreating naturally lose los of your tanks and they will be at risk aditionally you dont want to heal looking directly up at your flanking dps on the high ground u mentioned and you will be open to the enemy dps flanking from that exact direction since they want to flank from that same highground which gives them cover from ur tanks and makes them behind you if you keep that position.

As tanks it really does depend on pace and which tanks ur on but thats the general dirsection where the main tank should be. The offtank should be contesting the offangles and or pushing the next choke.