As an example, time after time I'm given taxi clearance then half way to the runway I'm given my clearance.
Best practice should be for clearances to be delivered PRIOR to taxi.We are told that the taxi phase is a critical phase. There should be no reason why you could not ask for your clearance BEFORE start...or in fact before you accept taxi clearance.
A phone call to the watch manager or a liason visit to the unit involved would go a long way towards ironing out problems you have.