I hadn't done it very much at all until last year coming down the USA Intra Coastal Waterway.
Every bridge was different, every current, depth, wind, width different and every bridge was the first time I had seen it and every operator does things ONLY in his/her OWN way!
Some bridges take 2 minutes to actually open from when they first start to move, some take up to 5 minutes.
Some operators at, say, 9am, wait for a break in the traffic, drop the gates and start the bridge. Some don't give a stuff about the traffic so its straight up. Some are still having coffee at 9:05.
Some dont open untill you are close enough to satisfy THEM.
Some want you through before he span is fully open, some will scream bloody murder if you are in the fairway 200 meteres before the bridge before their green light comes on.
So how does one "Stand By"? Well, you use every trick in your fast expanding book of tricks, all while you are learning new swear words.
The only really great bridge on the ICW is at Alligator River where its "on demand" when you ring on the VHF the guy just says: "yep I can see you, just come on up" and he opens it perfectly in exactly the right time and drops it right behind you without you ever having to slow down or speed up. He must own a sailing boat!
Some other the others are raving ratbags.
In Florida where the bridges are close together there was a group that theres no way you could do the group unless you could go just a fraction faster than any sailboat and the F'ing glee of the jerk slamming one shut after you have burned smoke to get there....
But now I am in the Caribbean and I am calm again............calm.......... Ahhhhhhhhhhhhhh