Experts on Brilliant Chemistry may have less availability then a full work week. Many of them are working full-time and doing work on the side.
An expert specifies the number of hours per week they are available to work with clients. This is the number in blue. In many cases, there is a number in red that specifies the number of "burst" hours available. Burst hours are available for unique situations in which a deadline or special circumstance occurs. These wouldn't be considered regular events and must be prearranged between the expert and client.