With you needing to progress to each biome I think it would be reasonable to have at least one for each biome with maybe an extra two for sub bases in single player at least.I think I have seen someone mention setting it to 10 per player. I really don't think there is a top limit that will break the game, though they may have a hard cap on them. However, if you have dynamic meshes enabled, that will start to cause performance issues with larger numbers of land claim blocks, I think. That is tied to land claim areas and tracks everything done in those areas to make it visible from a distance. If you are doing that for a lot of land claim blocks, I think it will probably start to cause performance problems. But that is just a guess.
I don't see much reason to have more. I rarely have more than 2 - one for my base and one for my horde base. And I often don't bother with the horde base. About the only time I'll have more is if I make a new base somewhere else later in the game and don't bother destroying the old land claim block.