I think most SBs appreciate exclusivity, but I think it's mostly just about their egos and it only applies to the daddies they really care about. All of my unicorns have gone exclusive with me without me asking. They break it to me as if I should be proud of myself (and I am proud I'm knocking their socks off). When this happens, I'm seeing them at least 3-4 times a week and it's obvious they're the ones I'm banging the most. They love it when I tell them they're my favorite and they're giving me the best sex I've ever had even though I'm going to continue seeing others, which is absolutely true at that point in time. They'll treat me like boyfriend, tell me they love me, bang me for free, text me all day and even get me small presents. What's interesting is that they don't seem to care that much at that point when I tell them I've slept with someone else. They'll usually probe a little bit to get a sense of what I thought, but when they realize the new girl didn't mean much, they're perfectly fine with it. What finally ends it with these girls is when it goes from 3-4 times a week to once a month. Then they realize that someone better has replaced them and they say things like, "I'm jealous!" and "I thought I was the one!" as they ask about the new girls.
As far as the more casual sugar relationships go, I've encountered SBs that just don't have the bandwidth for more than one SD and some that think more SDs makes them more like a whore. These girls usually don't ask too many questions though and seem to be more transactional about sugaring.
I have zero experience with SBs that outright ask for exclusivity because my profile weeds them out and vice versa.
I think if you accept exclusivity right off the bat, you're more likely to get bites from prudes, who are probably never gonna go through with it. For all of the SBs I'm usually interested in, encouraging them to see others makes me seem less creepy and more powerful.
If you demand exclusivity right off the bat, you're gonna get some girls that no one else wants. Why would a SB agree to ONLY see some old guy when hot young guys approach her several times a day? If she agrees, she's lying.