How does density altitude affect Taxi-Out Time?
The time between takeoffs on a given runway is a function of wake turbulence separation from the preceding aircraft, though wake turbulence avoidance times can often be waived by the pilot in command (depending on operating procedures).  Takeoff separation time is calculated based on aircraft type/weight.

An increase in density altitude could determine whether or not the aircraft can do an intersection takeoff, which in some cases could increase taxi time.