It's in good part because the conference is at its limits.
Scheduling is uneven. Talk A ends at 10:50, talk B starts at 10:45. Also getting from the H building to K takes a good while, and interesting talks tend to get full which is an extra reason to try to be early.
Unfortunately it's not a really solvable problem short of maybe making the conference a day longer.
I haven't been for a while but latterly I came to the conclusion that you picked a devroom for a day/half-day that you were interested in the talks/people and hung there. Or you spend the half-day networking/socializing. It's mostly an exercise in frustration to flit from room to room for specific talks.
Scheduling is uneven. Talk A ends at 10:50, talk B starts at 10:45. Also getting from the H building to K takes a good while, and interesting talks tend to get full which is an extra reason to try to be early.
Unfortunately it's not a really solvable problem short of maybe making the conference a day longer.