I’ve been curious about this for a while. When I use collapse vertices, I have an option to select “Collapse To First” and it all works fine, but it seems to me like it would make sense for it to use the Toggle Tool Handle setting instead. 
As it is, a lot of time when I want it to collapse, I expect to to collapse to where the handle is.
That is, if I have center selected, I expect it to collapse here (which it does)
If I have Pivot selected, I expect it to collapse here (but it collapses to my other point because it was selected first)
It seems that unity’s default behavior for pivots is to be the finally selected point, where as pro builder only gives me the first selected point. It would be really nice if these behaviors were consistent, I often find myself getting tripped up by this. I know these are fairly arbitrary decisions, so I don’t really expect this behavior to get changed, but it is something of a gotcha.