Lusternia has expanded enormously over the years, adding huge numbers of rooms to itself. As it does, each rank of Explorers begins to require more actual rooms reached to attain. In general, all that this means is that guilds with an explorer rank task need to occasionally adjust the required rank downwards, but at the upper end this leads to a few pressures & potential problems.
One of the biggest is the drive to "break in" to closed areas- not to actually look around or see the rooms, but specifically to increment a behind-the-scenes counter. This includes guildhalls and Divine temples, both of which are intended to be pretty private to a small group of individuals (much like the suggested Homesteads).
For guildhalls, a popular technique is to check WHO regularly until you spy a novice in a guildhall and try teleporting to them. If there is a lack of a monolith, you are able to abuse the ignorance of the novice to run around. For Temples, it is more popular to use an ability that can teleport you to a random room in the area (since the entrance area is small in relation to the rest of the temple the odds of success are enormous).
I think that a couple of simple tweaks could address this, and also cover Homesteads without needing to flag each Homestead individually as uncountable for explorers.
1) Set each Prime org territory to not count for explorers (immediately removing guildhalls, homesteads, arenas, and any future expansion from requiring invasion specifically for the numbers)
2) Set Divine Temples to not count for explorers (let the Realms still count, to encourage exploration)
Ar this point, breaking into these private places would no longer be a "requirement" but instead something done only if you are really interested in that location. You also reduce some of the total room count, making it a bit easier for an individual to gain ranks.