Well, my own experience of large experienced ewes was that I could never catch them at all with a neck crook. On the odd occasion I did get one around a ewe's neck I bottled and let her go, fearful of throttling her if I stopped her by the neck at the pace she was moving. I could get a leg crook on an adult ewe ok but found that unsafe for me unless I was in a restricted area.
You can catch them by the leg when they're feeding, but a hefty adult ewe will quite quickly pull free of a wee human lassie (or even a fairly hefty human lassie

) in an open space. And you'll not get close to them with your crook while they're feeding a second time. (Who is it says sheep are stupid? If they were stupid why would we all have to spend so long discussing how to outwit them???

)
If you can get the ewe or lamb into a restricted area, you can probably catch her/it without a crook at all once you have a bit of experience. But until then, I found the leg crook the better.
I can catch lambs in the open for the first day or two, using a crook which is sold as a leg crook for adult sheep; the hook is just the right size for the neck of a young lamb.
In a confined space I now generally scoop lambs up with my hands - you learn how to confuse them into falling over their own or another lamb's legs after a while.
