It depends on the number of panels versus the amount of detail and art I have on a page. If it's strictly black and white art, traditionally I work at 8 hours to a page a day. Digitally, I'm still assessing that.
If you add color into the equation, the main statement still applies- amount of detail versus panels, and effects. If i stick to a certain scheme and process, I can usually cut my coloring time down to about 5 hours(minimum) per page- and that has been since I've gotten adept at using my Wacom tablet; when I was coloring with a mouse it used to take me an entire day. The reason the process has gotten a little longer is that I discovered texture brushes; there's always a conscious battle to use texture/effects and make sure I'm not overdoing it
If you add in lettering, it's not too much. I usually go into lettering, knowing what I want the end process to look like- since I dont have a balloon template library/file(storage file for premade and frequently used word balloons) the process is a little slow. I usually letter a page at the rate of hour or less.
I dont draw/ink a page, color same page, and letter same page. I usually draw/ink most of my pages first, then comeback & color them, then come back again and letter.