if your using LRs in missions and searching a container next to a spawn point right as the next wave is about to come out, the problem is not the game, its your PvE tactics.
watch the zed closer, pay attention to the invisible "spawn timer", watch how your survivors react in different situations. you must be somewhat new yet if your having problems with these issues. yes spawn zones are clearly visible, yes there is a certain grace zone surrounding the spawn points.... setup your team accordingly. LRs are a bad idea for PvE unless its a FAL or SVD... but even then there are better options. there is also a timer from when the last zombie from one wave is killed to the spawn of the next wave.... pay attention and learn how to play the game. your survivors will not do everything automatically, don't be afraid to move your survivors around..... a lot..... especially your melee man.