Gelfy has half a sachet every other day. It means he can stay in work which means his hocks have a greater chance of fusing completely than if he was retired or taken off the bute altogether. Once his hocks fuse, he'll no longer have the pain that he's in now, and in theory can come off and stay off the bute altogether.
There is a risk that while his joints are fusing the use of bute will cause side effects, and also the small risk that any minor injury or lameness would be missed and made worse by working him; but without working him, and without the bute, his hocks will be highly unlikely to fuse and he wouldn't still be with us.
A couple of people have told me I'm being cruel working him on bute. But it's for a reason - and if his hocks don't fuse, he'll have a week of being dosed up to the eyeballs and turned out before being PTS. I wouldn't keep him on a maintenance dose just to keep him working.
Bute is like any other medication; it has it's uses, and it's absolutely invaluable in some cases, but it's open to abuse. The trick is simply to use it responsibly.