Continuous Come betting reduces the expected amount of clock time until you have lost your buy-in, compared to Pass betting w/o the Come bets.

Some of us want to have a certain buy-in last a long time (on the clock). Many of us have objectives other than house edge. Or make larger Pass/Don't wagers just on come out rolls for the shorter time. As for making continuous Come bets (or Don't Come bets), the house edge percentage is exactly the same as if you just made the same size Pass/Don't wager on come out rolls and played for a much longer time to get the same number of wagers resolved. If your sole objective is to minimize the house edge at a fair game of craps, then the ultimate strategy is 'Don't play at all.' I think second best is the Don't Pass/Come, with the Do being very nearly the same. The 'best' strategy depends a bit upon your objectives.