Presume that any building, cave or set of ruins that has any residents will have a sane number of traps, traps that can be avoided by the residents without having to perform a limbo dance or yoga exercise routine. If a walk to the john involves a game of hopscotch, you've included too many traps.
Thank you. That has been a big gripe of mine for a long time.
Presumably these places are (or were) in use by creatures who had to traverse these areas. If your common grunt soldier or 0-level servant has to go through that area as part of his regular duties, you can't have a diabolical trap that requires a master thief to disarm in order to pass without losing body parts.