I do pots in the River Camel and they seem to peel in cycles. As Arry says, sometimes get loads sometimes a few.
We do get them at night by lamping them but you’re not after the ones that put their dukes up, you are just spotting the jacks that are carrying a hen and removing her from him. Always leave the belly to belly ones personally but others take them. You can get hundreds at a time doing this.