To allow the duration time for any service to be 0h 0m when working with an assistant to allow client to double book online for services. Also, if you are able to click a check box for assistant for each service. For instance, if the assistant is applying a root color, then the stylist can be doing a haircut/blowdry. Clients can book online for each service for the allotted time of 1h each.

Another example, when a client needs a gloss after a highlight processing service, the assistant can be apply the gloss. During the highlight processing time (45mins) and gloss service (30m), the stylist is free to do other services (1h15m).