Buying a higher dosage (10mg) but only taking 2.5mg of it to save money. Is that a thing? Can it work?

Hey so getting Tizaro 10mg - that's 0.5ml prefilled syringe.

I will be taking 1/4th once a week of that syringe to essentially get 2.5mg a week.

I was wondering if that's a thing to save money? Buying a higher dosage than what you normally take and thus taking half or 1/4th of it. And if that works with prefill syringe