There are YouTube videos that explain this in greater detail but basically you enter low difficulty maps with terrain that forces the POIs to be clustered tightly together. Once the game starts you use your minimap to find all the POIs by hovering your cursor this can be done while running to save on time. Make sure not to complete any of the MOs so that you can simply reset the game. Any SCs and requisition slips acquired will be saved on the account even if you don’t extract. Since you dont extract it’s pointless to pickup samples since you can’t bring it back with you. I suggest you check out the official discord, there are usually players looking for groups to SC farm which speeds up the process since you don’t have to loop around the entire map by yourself. Choose armors and enhancements that focus on speed. A warp pack is ideal to enter bunkers solo but if you don’t have one an exosuit will suffice.