Flight School's concern: Boost pumps generally wear out quicker when they are used more, and they are expensive to replace.
Pilot's concern: Aircraft will stop running if boost pumps are off when engine driven pump fails.
Consider this: On turbine aircraft (such as every modern Bell product) even though the aircraft will run without the boost pumps on, we always keep the boost pumps on. Standard Operating Procedure.
"Pilot's discretion"
When making a PIC determination in regards to whether or not to accept a flight or whether or not to have an aircraft repaired prior to that flight, cost should never be considered. Any company that even blinks, when something needs replacing, has no business operating a helicopter.