Does Finasteride lose ability to inhibit hair loss when it's cut into quarters all at once? Should I cut them daily as I use?

Cutting 5 mg finasteride into quarters does not impact the active medical ingredient finasteride. They can be stored for a long period of time as cut tablets

When you break up a manufactured pill such as finasteride, these cut pills are more susceptible to absorbing water moisture out of the air, so if you feel you must cut them, do that daily