Been using the quiet-wean nose blabs for several years; previously, we 'weaned on the trailer' - but that's not good for the calf, the next person down the line - or the beef industry as a whole.
We have confined spring & fall calving seasons, so all calves in a group are within a few weeks of the same age when weaned.
Year-round calving...I dunno...I'm not planning to go back to a 'no management' system. Before we started this, I'd sometimes have a cow calve out while the previous year's heifer was still nursing - makes it hard for that new baby to get a good start.
Nose blab insertion works in well with the final pre-weaning vaccination here. Calves are typically held and fed a little for 2-6 wks prior to sale.
We try not to leave them in longer than 4-5 days - noses start getting ulcerated and goopy if you go much longer. Have had well less than 1% of them manage to get 'em out, and maybe ONE that figured out how to nurse with it in. Have been re-using the same batch for 3-4 years. I just drop 'em in a bucket of soapy water to soak, hose off the worst stuff, and run 'em through the dishwasher(don't tell my kids!)
Almost no bawling by the calves once we pull the blabs and separate 'em from the cows (separated by a 16-ft alley) cows may call for the calves for a day or so, if we don't move 'em out.
Didn't use 'em with one group a year or two back, just separated cows & calves, and after dealing with constant bawling right behind the house, the farm manager said, "Never again."