The idea of switching systems based on the what the market is doing would work well. Using an indicator like ADX to tell you when to scalp and when the market is trending might work. The only problem is that I find the ADX too lagging.
Lately, I've been more interested in taking unprofitable systems and switching some of the parameters in order to make them profitable. There are a lot of systems out that give horrible entry prices. If you buy rather than sell or sell rather than buy when you get a signal, you could make a bundle. Just stop and reverse when price goes against you X number of pips.