Time is naturally the first variable in the route planning process. If for example, under threat of losing your job, you only have four weeks to complete the Rally then you probably shouldn't be driving via Pakistan. Be slightly realistic here - there's no point in adventuring across half the world if your memories consist of tail lights and petrol stations. Pack too much in and you don't allow time for getting lost and stuck. You’d be better off covering a shorter route or pre-empting the inevitable sacking and quitting anyway.
As a rough guide the northern route usually takes 3-4 weeks, the central takes 4-5 weeks and southern route takes 5-7 weeks.
Click here to read the story of the longest and shortest time taken to do the Rally.