I've been playing my current character for four hours and have not seen any other non-zombies. At all. The problem has never arisen yet for this one. My anxiousness around other players runs higher as I aquire more gear - any player might want to kill me for my beans, or fun, whilst newer players might want to kill me for my AK47. It's also heightened at the moment by the fact I'm north of Berezino where I know a lot of groups have a "shoot first" policy (and I'm likely out-equipped by a lot of the players in that area). Overall though, I'll avoid anyone I don't know and only shoot people who point guns or are so rude as to actually shoot at me.