I have given up even attempting to turn sheep now as my back, neck and arthritic hands won't play the game (neither will the sheep!). Many of mine are great big bruisers especially a couple of the rams and wethers. I invested in a turnover crate last year and for those big sheep and the bigger ewes it's been a godsend. Mind you they can still kick and struggle while upside down! It's no good for the narrower Gotlands who just spin round in it, but they are small enough to be handled.
I'm in awe of the young lad who does my shearing, he whips through the lot of them without even seeming to sweat ..
. I prefer to dag them standing up, I think you can get to more of the fleece - it's easier for me to get my knee into their sides to hold them in place while hubby or friend hold the front end! I think I may also invest in a headstock.
It's actually quite amazing what sheep will go through and still come back for more of the same following a bucket. Turning them over in a crate seems quite a traumatic thing to me but they can't be that stressed (or have a very short memory) as they come back again!