Thanks to everyone who shared their experiences, very interesting. My personal two take home is that 45 minutes is a much shorter connection in reality than on paper. I think I'll take that into account a bit more when choosing connections.
Oh, and that sometimes when you late really close to departure you should relax and save yourself the run through the airport. Now whether I'll actually be able to bring myself to do that when I deplane at T-10 we'll have to see.
It is. I've almost always 'run' literally as fast as my young millennial legs can go from one connection to the other if it is listed on paper as 45 minutes.
Best advice on this thread is if you think it's tight, such as at T-10, ask the gate agent upon deplaning to radio ahead and inform them that you're coming, to leave your ticket valid, and to hold the plane. While not guaranteed, it may help!