Nowadays there are paths up, along and down most Munros. The less frequented Tops may just have paths along ridges between them with few discernible paths lower down. The most popular mountains have fully engineered paths all the way to the summit.
Lower down there are almost always gates or stiles in fences and walls where a path crosses them. So paths can be picked up at those points. Higher up, as a rule, paths become more distinct and more easily found as the summit is approached. The reasons are obvious: more feet per square yard and a smaller area to search. This means it should also be easier to find the start of a path going down rather than up a broad ridge, and easier to find a path on a narrower ridge than a broad one if they are equally popular.
For very steep, rocky sections when no path might be found, it is easier to select the best route when going up than when going down. This is because the concave section at the bottom gives you a view of the steepest parts ahead, whereas the convex section at the top hides the steep part below.
Unless they are properly constructed, paths often have long sections of peat bog which is full of deep porridge-like mess in summer and covered with insecurely thick ice in winter. I might then devise a route away from any paths. Clearly, valleys and wide bealachs are worst for this as water and snow collect there in a way that they don't on ridges. Thus, I always favour a ridge walk over a valley one when possible, especially as the views are usually more spectacular.
Fully engineered paths are all well drained. There are some on Ben Nevis, Ben Lomond, the Torridons, the Cairngorms, Buachaille Etive Mor, etc. I personally don't like the latest design which seems to be prevalent: they have stone throughout and no gravel or turf, presumably for permanence, and are crossed by culverts with very proud edges, presumably to stop mountain bikers. These features make them very hard on the feet and joints, and force one to break one's stride. The widespread re-building of those in the Cairngorms has definitely been a retrograde step. Usually the gradient is reduced to a minimum, which can be very frustrating: I've sped down one such path (from Maol Chean-Dearg) at over 4 mph but taken a full hour to cover one mile as the crow flies.
Vegetation can be a problem to the walker at low level. Bracken, heather and brambles can all be a pain especially in rain, so that paths are generally desirable on lower slopes. Forestry commission plantations should be avoided except for clearly marked paths and roads. Off the beaten track they are extremely dark, dense and strewn with dead branches and drainage ditches. I've had to use a compass in them (one, now gone, NW of Beinn a'Chleibh) because there can be no view of anything but trees.
Copyright © 2007 & 2012 Colin Walter