Coloring. I actually gauge how much time a portion of the process takes by how much of my 'watch later' list on YouTube I watch while I'm working.
Laying out panels and word bubbles? Hour and a half.
Actually drawing the panels? Depends a bit, but usually 2-3 hours.
Inking? Hour and a half.
Coloring? Like... 4-6 hours.
And then I do things like re-inking lines that got faded during the coloring process, scanning, editing, etc... but coloring is the worst chunk by far. Even for easy pages.