Well sure, I need to relog occasionally for instance when I want to pay off newly incurred fines, get an engineer invite, or the instance is somehow bugged, etc. The need for those relogs would seem to be bugs to me.
Regarding relogs for loot it's rather inconsistent. If you relog at a Horizons site a normal relog to main menu is enough, a relog at a HGE must be a complete relog to desktop. In Odyssey if you have a mission to a POI like a crashed satellite it will disappear at relog if you took the mission item, but if you didn't take it then the satellite and all mats/data will still be there at relog.
If you have a mission to get something from a settlement then a relog after landing will remove all mats/data except for the quest item.
One of the coolest relog exploits that I've seen is at the Odyssey sites with the 3 containers that give weapon schematics. Pick up all the mats except for the quest item, then relog inside the container. You'll reinstance inside the container with the door closed, you can loot and no scav can get to you...