Driver power handling is based on the frequency distribution in 'typical' music. So if an overall speaker is rated at 100W, it definitely doesn't mean you can run each driver at that level. So, in general, the higher the frequency range, the less power a driver can handle if connected directly to a signal generator. Even if you are trying to test each driver through the crossovers, and not directly connecting a driver to a signal generator, there is a limit to how long high frequencies drivers can take sustained tones.
Also, crossover have overlap - their bandwidth on each output does not look like a square wave. Sometimes I use a cardboard tube between my ear and a driver to focus on sound coming out of the particular driver I'm interested in.
