No way a bottom can demand a Top's load, even in a 1-1 situation. As a sub bottom, I can beg or ask for his load, but it's really up to him to decide if he wants to breed me with his unique DNA.
If I'm going to bend over at a bathhouse, sex party, etc., then I'm telling the Top it's OK to sample my hole. Period. Here's my hole. You do what you want.
I actually enjoy having multiple Tops just stretching my hole with a few strokes, and moving on to the next hole. Every cock is shaped differently and so is every bottom's fuckchute. Some cocks are a better fit than others. I enjoy just having a man's cock sliding in and out of my fuckhole. If I'm at the baths or a sex party, there will always be another cock ready to sample my cunt, and make me work to earn his load.
A Top will know when he's a good fit, and I will work my ass off, litterally, to milk his cumload out of his cock.
But it's always the Top's choice to breed me, and not for me to demand.
There probably are six or seven bottoms for every total Top. Bottoms have to compete to get the Top's load.