Sometimes I've felt like being with a partner as soon as a couple hours after they've been with somebody else. Sometimes I haven't, and that's usually due to if my relationships needs with them are being met, how well we've been getting along, and my comfort level with the metamour in question. Regardless of if it was me or them on a date, sometimes my partners feel like being intimate with me, sometimes they don't.
I find a couple of hours of transition time helpful, so I'm present with the person I'm with. My husband finds he isn't often interested in being intimate with me on a day I have a date until he has an activity that gets him out of the house to reset (work, hobby, movie) but that's not always the case either.
I recently had a date change nights, and so ended up being intimate with a partner in the daytime after they'd spent the night. They said they wouldn't really have wanted to have sex if my plans were still on that night, basically out of "respect" for my the person I'd had a date with. I find it interesting that he didn't think, "I'll refrain so you have your energy for your husband," but viewed an outside partner differently.
I think a lot of people view live-in and non-live-in partners very differently. I know I don't think anything of my partners going home to sleep/have sex with people they cohabitate with, but I have found that I can be a bit uncomfortable in new relationships when a partner I don't live with has a date with me and somebody else they don't live with in the same day, while I'm trying to get comfortable with all the relationships. That's silly, because either way, they are probably (and hopefully) having some lovely sex. Nevertheless, I wouldn't have thought twice about being intimate with both my non-live-in partners the same day, unless it would keep me from being a good date to both of them, just like I didn't think twice of wanting to get my husband naked since he got stuck with me that night.
Yep, that's all kind of a sidetrack of your question, but I'm glad to have a reason to examine my feelings on the subject! I have some thinking I want to do about this. In one relationship, my metamours are all super busy and I'd hate my partner to not be OK making plans if something opened up because it wasn't "respectful," as long as all parties are fine with it. And although he's had a couple back-to-back dates, he tries not to schedule them out of this here "respect" thing.
I think I'm going to tell him to grab life while he can.