>>369810530
Story missions are rarely worth the ammo and heals and repairs you spend on them. Same with nice chests, they're usually never worth the ammo you spend clearing the area to access them. Since spawns of those chests are semi random you should basically keep note of the lesser defended ones and check those areas whenever you're nearby. For example in factory there's a spawn point up the side of the story building that you can get to from the outside. It's on the same side as the floating stairs anomaly. In Kolkoz there's a substation with a bigchest sometimes that's almost completely undefended - contrasted to the one in the greenhouses which has 15-20 mimics to blast before you can get to it.