I am no expert. I have developed a feel for training. It is much easier to do than to describe. I had a good, long laugh at Olga's recent pictures of her pruned roses. They look exactly like mine (of the same class). Exactly. To hear us describe what we do, you'd think we were doing something really, really different. Ha!
It's as simple or as complicated in mild zones (8b-9a) as the heading. There comes the day when all the bud eyes on a cane have been used up and are never going to be productive. It's time to remove the cane.
Sometimes the cause is the location of the cane (say down at 12 inches on an 8 foot plant). Auxins won't go there no matter what you do. Sometimes the bud eyes have produced so may successive flushes that the center of the plant's growth has moved up and on. Again, the auxins won't go there.
Roses vary wildly in their ability to repeatedly produce new canes from the same bud eye. They vary wildly in their ability to push growth from dormant bud eyes down low. They vary wildly in their demand for cane shortening. Some actually must feel the steel to perform, like some of my floribundas and HPs. Some like no pruning at all, like my spinossisimas. Some are just fine being mowed to the ground every 5 years or so, like some of my suckering species roses from ecological zones where fire burns off the tops every 7 to 10 years. Of course I have to wing it when I encounter exotic roses from obscure classes (hybrid bourbons, anyone?). I only hope that I am able to study an unpruned plant, so I can determine its growth habit rather than one that has has had the ends of all its canes mechanically shortened every year.
I do so agree with Jon. I've never known a bud eye to be produced by cutting it off through cane shortening. So whenever a plant produces a nice long new basal, I cannot understand why anyone's first impulse is to shorten it to the height of all the rest of growth. Instead, selective removal of the oldest of the shorter growth is the first move, with the expectation that the rose wants and needs to be the size of the new vital cane. If I'm right, the rose should produce another new cane this year, leading to the removal of more old growth next pruning season.
Those of you who must reduce the size of your roses to fit them in small places no doubt train with that objective. That doesn't mean to repeatedly shorten new, strong growth without removing old growth. I see this in volunteer-pruned plants in large public collections: everything is shortened all over the plant with no executive decision ever made to remove the oldest canes. The result is that the rose ends up having all the new growth cut back, say to fit in an allotted space. It becomes a mass of old wood because volunteers, or anybody else, for that matter, rarely knows enough about every class of roses to formulate a plan for the selective renewal of the plant as a whole.
Q