I'm looking for best practices in regard to customization of issue types.
In an enterprise setup with 100 teams that are using the same Jira instance and want to use custom workflows and fields, how show I handle the customization requests?
That's annoying for the end-user - presenting them with fields they don't need on an issue type is not friendly, and a good admin will keep the fields as simple and clear as possible to save them time!
On a technical level, many fields is one of the ways you can cause issues. Performance is quite a complex thing in Jira, but each and every different field causes overhead you would want to avoid if you can. But you can minimise that by limiting the context of fields. (On this one the short answer is "a field that only exists in project X on issuetype Y is more performant than a global field")
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