Yes, ER. I have done a lot of wrapping.
As with many things that are done as a part of grooming and care, it takes consistent and regular work to see a difference. Support wraps sooth and protect by removing the stiffness and achyness, providing warmth, and if you use a liniment or paint, help increase circulation. The key here is OVER TIME. Don't expect miracle results overnight.
There are those who argue with that concept, but racehorses have been wrapped for a hundred years or more. There may be scientific and modern evidence to the contrary, but puffy horses and horses with problems are often helped with regular wrapping. I know hundreds upon hundreds of horses are "done up" daily and it can help support joints under stress.
Wrapping hocks: usually I would do this when I know the horse is going to be stalled. Hock wraps can restrict, and can slip down. You would want to put a hock wrap on when the horse comes in to eat dinner, for instance, and then is stalled overnight before turnout in the morning, as he's likely to be quiet and sleep most of the night and thus, be less active. You'd want to remove the hock wraps before turnout of course. I think that would give you the most effect for the work.
I usually use a neoprene boot with velcro tear off straps and sweat the hock, rather than wrap it, bec. I think it helps the horse more than a wrap. You can easily cord a hock because there is a tendon that runs just over the cap of the hock that is quite close to the outer layer of skin -- so a figure 8 type bandage can be very risky. Unless a horse is injured or has a break in the skin requiring such a bandage, I would stick to neoprene type hock wraps, supported by a common stable bandage on the cannon bone and ankle. I would not turn a horse out with same, too likely to slip or displace and then a kicking fest can get started!
I've used a magnetic wrap, Norfields, and a competing brand but not Back on Track. Magnetic wraps should not be neoprene. (Norfields hock magnet wrap is cloth with velcro). Neoprene will sweat and create moisture. Not sure if that will interfere with the effect of the magnet -- I assume so, since moisture may not allow magnetic field to work correctly.
Wrapping hocks: usually I would do this when I know the horse is going to be stalled. Hock wraps can restrict, and can slip down.
I also wrap hocks when they are going to be stalled. To prevent slipping down, I put standing wraps on the lower leg/cannon bone area first. To prevent restriction, I do a figure 8 wrap, avoiding the point of hock. Also, putting almost used-up vet wrap rolls on either side of the achilles tendon (tendon coming up just abobe the point of hock) will help alleviate constriction there.
I've never used boots- always just wrapped with poultice, liniment or a sweat under the wrap.