Some of my drawings can take many hundreds of hours, while others can be quite quick.
I used draw for very long periods, very long drawing marathons that would last 4 to 20+ hours and longer. Now, I tend to draw in smaller bursts. So a 10-hour drawing would consist of 5-(2)hour bursts or 10-(1) hour bursts, etc. Lately, I tend to even shorter time periods, like a whole bunch of 15 minute sessions, going off and on with various time-periods between them. This type of time-pattern with drawing can take all day. From the first of the morning until time for bed. I love days like that. Whatever the time periods, a full day of drawing is a very good thing. I believe being (out-of-drawing) shape could be contributing to my shorter drawing periods.
I believe a 100-hour drawing, drawn in 10-(10 hour) segments will reach deeper than a 100-hour drawing drawn in 100-(1 hour) segments. At least, that is one of the elements of my drawings I am trying to understand further.
I tend to draw more slowly than in my past. I was very much a gestural artist, I am not sure what I am now. Sometimes drawing slowly gets me there faster than the fastest of drawing. However, a 1-second drawing is as important as a 100-hour drawing. Right now, I am tending towards exploring the time-intensive nature of mark-making. But I do love to draw fast. Very fast.