Limit of 20 here in 2C. When I first move into an area, I make castor mounds with 330s. If they become shy, I use snares with castor mounds. If its a larger colony, I use castor mounds with snares due to the 2 body grip limit. I don't bother drowning beaver any more since I don't use footholds. Its just so much faster to use body grippers and snares.
Most of my spots involve hiking or jogging in quite a ways, so I need to carry as little equipment as possible. First, I hit my established beaver colony spots which change year to year. It takes a good bit of effort to locate these spots. I do this scouting in november when they are all set up for winter. Then, I spend march setting travel ways to catch those cruising spring beavers. Same types of sets.