Suppose you went into a fancy restaurant and ordered a delicious five course meal for you and the whole family. The cooks slave away preparing everything then the waiters and waitresses bring it all out and set it on the table.
You look at the pile of prepared food, turn to the waiter, and say...
"I don't want [THIS ONE] or [THIS ONE] or [THAT ONE]. Please take it away."
All that time, all that effort... gone. Time wasted, money wasted, for nothing but your "good pleasure."
It's not that much different in pharmacy when you ask the pharmacist and technicians to "fill all my meds" and then at the pick up window you say, "I don't need all these. I just want [THIS ONE] and [THAT ONE]."
At the pharmacy we can return items to stock and fill them for someone else... in MOST cases, but the idea is similar. We've wasted a bunch of time, effort, and money filling prescriptions for no reason.
Please have the respect for your pharmacy team NOT to do this. Don't ask us to fill "all your meds" if you don't really need all your meds. Ask for the specific medications you need. We won't waste time and effort for nothing. Our time is valuable, and expensive. And we don't need extra practice filling medications.