Depends on the situation. If it's an EXP Party, try and find another spot, in the long run you'll be better off anyway. With NMs/Keys I've been fairly lucky, several times we've fought our way into the middle/back of a stronghold to find another group already there, the other group recognize that it has taken us time and effort to get there too, so worked out alternating claims, with both groups killing the NM to speed up respawns.