Two small decisions shape your GR20 far more than you would expect: the direction you walk it in, and the stages you decide to run together. On paper they look like nothing, but they shape your whole crossing, from the fatigue you build up to the sheer pleasure of the walk. Here is how I settle them with the walkers I guide.
North to south: the direction I recommend
I recommend starting in the north, from Calenzana towards Conca, for two reasons. First because it is the traditional direction, the one most walkers take, so the one where you will meet the most people and find the most mutual help. Second, and above all, because you begin with the hardest section, while your legs are still fresh and your morale is at its peak. The north is technical, demanding, at times vertiginous, and tackling it at the start rather than exhausted after ten days changes everything. Once that first half is behind you, there is real relief in moving into a gentler south.
There is also the symbolic reward. Arriving at Conca, you pose proudly beside the famous sign, with its legendary spelling mistake on the word odyssée, announcing roughly 180 kilometres walked. Starting from the south, you will not get that honour, because there is no equivalent sign at Calenzana. Walking south to north remains perfectly possible, but it means saving the hardest part for the end, once the fatigue has piled up, and I would advise against it for a first crossing.
Doing only the north, or only the south
Short on time, or on training? Nothing obliges you to do the lot in one go. Plenty of walkers take on only the northern half, the most spectacular and the most technical, or the southern half, more accessible and kinder on the legs. The train that serves Vizzavona, halfway along, makes that split far easier: you can join or leave the trail without a logistical headache. It is an excellent way into the GR20 without committing to a fortnight, and a good way to come back later and finish the other half.
How do you choose between the two? If you are after the grandest scenery, the ridges, the mountain lakes and the technical sections that made the GR20’s reputation, head north. If you would rather have easier walking, pine and beech forest and more reasonable ascent, the south will suit you better. Either way, allow a good week for a half crossing walked at a comfortable pace.
Should you double up stages?
If you are fit and properly trained, you can double up certain stages by holding a faster pace than the one posted on the signs. In practice that means walking eight to eleven hours a day, bearing in mind that on the toughest ground in the north you sometimes cover no more than a kilometre an hour. Doubling up is not simply adding two stages together, it means accepting days that are far longer and far harder. Before you commit, ask yourself why: often the real obstacle is not physical, it is just difficult to block out a full fortnight of holiday or to take on the cost of two weeks in refuges. If you have the time, take it. The GR20 is as much to be savoured as conquered.
So which stages should you actually double up?
If you do have to condense, here is what a classic ten-day split looks like. The principle: keep a single stage on the hardest days, and double up the short ones. That gives you stage 1 on day one, stages 2 and 3 on day two, stage 4 on day three, stages 5 and 6 on day four, which makes the biggest day at around 36 kilometres, stages 7 and 8 on day five, stage 9 on day six, stage 10 on day seven, then 11 and 12, 13 and 14, and finally 15 and 16. The same scheme tightens further into eight, seven or five days for the most seasoned, with days that sometimes come close to 50 kilometres. The golden rule never changes: double up where the ground runs easily, never where it climbs and turns nasty. You will find these condensed plans in detail in my ebook.
My advice, in the end, comes down to one sentence: pick the format that lets you finish relaxed, not wrecked. North to south for the logic of it and for the reward at Conca, one half only if time is short, and doubling up only if you are genuinely prepared. The finest GR20 is not the fastest one, it is the one walked at the right pace, your own.
To go further, see which preparation for how many days and the full 16 stages.