Spiritual Population
The number of elohim around at any given time is something you can flex to your needs as a Host. Here are a few general guidelines to help you along, but they are by no means hard, fast rules.
Until the great Day of the Lord, the kingdoms of the earth belongs to Satan and the princes whom the Most High assigned over the nations after Babel. The unclean spirits roam free to harass unrighteous humans. There are also holy watchers on assignment or maintaining Holds, but they are overall in the minority.
Elohim of any variety are more likely to be around humans and concerned with human affairs. Therefore, you are more likely to come across a high number of elohim in cities and densely populated areas. In cities, it is more acceptable to have both holy and unholy elohim coexisting, each concerned with their own goals and only coming into War when their goals clash. That being said, there are always those on either side who may seek War without a strong reason.
The official lore does not provide every human their own personal guardian angel. Neither is there a demon on every shoulder. Primarily, these concepts are not a part of ancient belief, but also as a Host, you would quickly find either of these to be impractical and inconvenient to consistently enforce.
The wilderness is generally viewed as a place where demons hold sway and as such, travelling holy watchers may come across patrolling bands of unholy enemies. These unholy elohim are more likely to be hostile, especially if they have nothing better to do and think they could win in a fight.
Ruins and cultic high places are viewed as places beasts and unclean spirits congregate. They are best avoided unless purposely raided in order to thin out the numbers of demons building up there. If not addressed, they occasionally will flow out into nearby populated areas for a night of havoc, stirring up any and all sin they can muster within the local populace. These incursions will often follow the signs of the sun, moon, and the other heavenly bodies. This is about as close to "dungeon diving" as you will get within the lore. Contrary to popular portrayal, caves and underground chambers were not common sites for religious cultic practices. Instead, high places and temples with gardens were much more common, as they brought the worshipers closer to the heavens and thereby closer to the gods.