I do a lot of planning.  you have to for the long loop trips I like to do, travelling every day but for one layover day (usually).  I "need" to be halfway thru the loop by mid-trip so I can get back on time.  I do a detailed itinerary breaking up the trip into segments - each lake and each portage, by how long I estimate the segment to take, and total up the pieces into a longish travel day or 10 or 12 hours(thoug I'll often alternate shorter days with longer ones) - then I fine tune the trip if I need to cut off some miles somewhere, or maybe plan a sidetrip if I have that extra time.  I've been thru most of the park, so I already have those segments figured out from previous trips, so its not that much work to lay out a days travel.  Usually, I alread know the campsites, but if moving thru a new area or someplace I haven't been to for a long time, I will use the PCD to check them out.  I'll generally have a destination campsite in mind for the end of each day, along with several other choices as backup in case the site I wanted is taken, or if I have to stop short for the day.

Gear is pretty easy - just go thru the checklists.  Much of the stuff I take to Quetico is Q-centric - its just used for Quetico, and stays together in a box.  Packing the food is what takes the most time for me.  Then its fine tuning the gear and food to get the weight down to what I'm willing to carry.

its easy to not do any planning if you are taking 10 days to travel a 5 day loop, or just base camping - but to cover a 10 day loop in 10 days, you need to plan a lot better.