I think you are talking about "transit" time rather than digestion time. Generally most food has been broken down and the major components absorbed within 3 -4 hours. If you will monitor your blood glucose after eating you will find that it starts rising as you eat and will continue to slowly rise for 2 - 3 hours where it reaches a peak and then starts to decline. This will happen regardless of whether the food is cooked or not. The over all speed of the rise as well as the peak reached will be dependent on Glycemic index of the food. Generally if its mostly carbs it is digested faster, maybe an hour or so total, but if it is mostly fat and protein then 3 hours is more the norm.
Total transit time for the waste products resulting from eating a meal may take anywhere from 4 to 6 hours all the way up to 24 hours or more depending on the health of the digestive tract, how often food is consumed, and how irritating the food is to the walls of the intestins and bowel.
As an example, if a person eats white bread it will digest very quickly causing a rapid spike in blood glucose, but the waste products create a sticky mass that moves very slowly through the intestins and bowl and may not be expelled for several days. On the other hand, if a lactose intollerant person eats dairy along with their meal, the body will react strongly and push the whole mass of food eaten with the dairy products through the digestive system and expel it within 3 or 4 hours (with much gas and cramping I might add).
Someone eating raw meat and fat will have very small stools as there is little waste. With little bulk there may be no urge to defecate and expel the waste products until sufficient mass builds up in the colon which could take 2 or 3 days. Unlike the white bread scenario however, there is no feeling of constipation as the problem is just a lack of enough mass to trigger a bowel movement rather than a sluggish sticky mess that is difficult to push through.
As you can see there really is no simple answer to the question of total "transit" time, but you can monitor "digestion" speed yourself just by tracking your blood glucose curve after eating your meals.
Hope this helps,
Lex
