Many athletes and coaches include hill reps in their training schedules somewhere but they do not all do it the same way. Many road runners deny ever doing rep sessions but when you ask if they do hill training, almost all do! Why do they do hill training? First it is a leg strengthener. There have been a number of investigations into this aspect of the sessions. The first one that I know of is a French one where runners of comparable ability were divided into three groups: one lot did their usual training, another did specific weight training and the third did hill reps. The weight trainers had the biggest strength gains but the hill runners were not far behind with those doing their normal running well behind. Second with the hard work up the hill and the short recovery it is a good heart and lung improver. There is also an effect on the sprint running action with a full leg extension being required along with a higher than usual knee lift.
Locally, Jim Murray who ran for us in the 70's and who lived in Partick did a square starting at the foot of White Street: he ran up the hill in White Street, went right along the top, right down the hill, back along the bottom and then sprinted up the hill again. Doug Gemmell simply sprinted hard up every hill he came across in his steady runs no matter how tired he was at the time. Robert McWatt ran up the Goldenhill Park from the paddling pool straight up across the path to the top. This was particularly hard in that the path broke your stride two thirds of the way up making the last bit really hard. I used this one with Grant, Ewan, Kheredine and Graeme Reid. Bobby Shields invented the X Run in the High Park at Thomson Street. Starting at the Library in Hawthorn Street, we would run diagonally over the top of the Park to the corner at the Health Centre Car Park in Thomson Street. We would then jog along the edge at Thomson Street and at the bottom corner it was diagonally over the top to Hawthorn Street again before jogging back along to the Library and starting over again. Seriously hard.
There is a lot more to be said on this and if anyone wants more, just email me and I'll add to this post.