I use BLC in the following manner. I fill a keg with about 2 gallons of the solution (BLC and water, follow the label). I have four tap lines that I clean, so I connect the keg to the lines and run the hot solution through the lines for about 20 seconds. I do this with each line. Then I go thru the lines again for another 20 seconds but collect the runoff into a bucket. I then soak the keg connects from the tap lines in the bucket to clean the connects. Per the instructions, I flush the rest of the lines with ice water. I'll do this every 3-4 months or if I let the lines sit for more than a month without a keg attached.
Once a year I disassemble the faucet shafts and the entire faucet and soak everything in BLC to get all the crud off. There is usually some buildup inside the faucets, but it comes off easily. You only need to soak things for about 5 minutes in hot BLC solution. Rinse everything in ice water.
In between kegs I flush my tap lines with hot water, no solution. That keeps the lines mostly clean, but the quarterly and annual clean ensure that everything is clean. YMMV.