Is once a month enough for a D/s dynamic?

[Da****]

You can make any frequency work, but the longer time between sessions then the more work you'll have to do in the meantime. Don't let it become stagnant during the in-between. If possible, remain in close contact in between sessions - Video chat, text, whatever works. Get to know your sub better and build a dynamic with trust openness at the foundation of everything. Involve your sub in the creating of scenes. Discuss topics within the community, you'll be surprised at the ideas you can come across just by discussing the things each of you have seen or experienced.

I personally like to get to know my subs on an extremely deep level. I need to know what makes them tick, what makes them who they are. Through this, you may discover unfulfilled needs or the deep-darks that need to be brought to the light.

[Da****]

Also, multiple play partners entirely depends on your individual dynamic and relationship. If it's strictly business, then it may not be a problem at all. If it's more of an intimate relationship then you will need to discuss the idea of other partners extensively because in that case, you're talking about an open-relationship or non-monogamy, which may be an entirely new thing for one or both of you.