I've heard n seen video evidence of proper European pollarding, in which the arborist/climber leaves one wild un-pollarded hair intact to insure the tree doesn't go into shock.
That's precisely not the proper way. I know it was very common in the country but the "one linb left alone" thing was used to produce firewood in the edges between the fields, instead of wasting a good field/pasture to grow a wood lot. Usually, they harvested the limbs every seven years, (same as the common length for the rent of the farms), keeping the trunks there for a faster regrowth and not disturbing too much the edges. But the tree's health wasn't a concern.
It's very different from the pollarding used in the urban areas or the humanised landscapes, like castle alleys or courtyards. The purpose is to keep the tree always in the same shape and restrained in the same volume (actually oscillating between the "haired" volume and the "bare" volume). The other goal is to keep the tree in the best sanitary state possible, impossible to obtain with hard prunning. The crape myrtle's prunning shown by Mellow is exactly that. It was used with the same technique in the country too, but for production of annual sprouts like wicker (willow) and fodder for the live stock (ash). In these cases, there were just a few heads, or even just one over a short trunk.
Always start with a young tree and begin the prunning when she reaches the "bare" volume expected in the established tree. Then you cut the new sprouts back to the same places, but without touching the collar of every sprout. Small diameter cuts are the best, ideally every year. Every 3 years is a stretch to reduce the cost/worry, but it's less than optimal. Over 6 years, you get allready big regrowth, aka big cuts and good entry doors for the rot, so, basically, you enter in the hard prunning domain.and began to compromize the tree's structure (way too frequent these days).