How many ( ) needed to change a light bulb

In both the nest and the warren we have many types of lamps. I don't think any two (except for the bedside lamps) take the same kind of light bulbs. They all have different sizes of the screw in part.

There are two stores in the village that sell light bulbs. Sometimes they don't carry what I need and it is necessary to go out to the industrial area (yuck).

How many stores are needed to change a light bulb

What is wrong with standardization?????*

*Said by the woman who worked for two standardization organizations NFPA and IEC.