I learned to fly long before GPS was invented and I still know how to plan a flight on paper with a sectional and I would still be comfortable doing it without GPS, but it has been a few years since I have done it. Currently I have Ifly GPS on my tablet so I have legal sectionals and approach plates if needed and I have it on my phone as a backup. My primary GPS I use in the plane is a 496 with XM weather, but I also have a GPS moving map on my GRT EFIS (that I don't always use because it is cumbersome to put flight plans orher than a direct to in it, but it is also my autopilot so doing that more often now) and I have a Garmin GPS155 that is there as a legal approach certified GPS so I can file IFR flight plans without having to go VOR to VOR when I finally finish my IFR rating. I also have an SL30 with the VOR and ILS input to the EFIS. So I have two belts and four pairs of suspenders.
I used to plot plans with paper and sectional when I first started using GPS. The reason I stopped doing it is because these days when I fly I almost never know what altitude and winds aloft I will be flying until I am in the air. Sure I could call for weather, and still do, but the altitude and winds aloft I would plan on the ground are almost never what I actually use in the air. Living in Florida there are always lots of clouds and storms around. My plane climbs like a bat out of hell and is efficient up high so I am usually 7-12 thousand feet on top of the clouds. Weather reports you get on the ground normally have base height of layers, but not tops so unless you want to plan a flight at 2,500' with thunderstorms around that you can't see and go around you don't know what altitude you will be at until you climb and look around. I am also covering a lot of ground quickly so I might climb to 14,000' to get over clouds or might descent to 6,000 to get under or might divert around a storm. Can't plan for any of that on the ground. And since I might be making 170 MPG ground speed or might be 230 I usually make my fuel stop decisions in the air also.
