Just wondering if anybody is in this kind of situation. Let's say I need a fix or a custom feature for a module that will be the same fix/feature for multiple clients. How do you handle billing for this kind of work? Record the time and split it among all the clients? Bill each client for the total amount of work as if you did the fix/feature each time? Bill one client and let the others get the fix/feature for free?

This is happening more and more for me and I have clients on monthly retainers so I make fixes and updates on their request or when I am working on my own features.

For example, recent Drupal updates to CKEditor broke a lot of features in LinkIt, Link Attributes and other related modules. I was taking part in the issue queues, testing solutions and reporting on fixes. For other modules, I provide my own patches and merge requests for the modules.