In theory, you can use UTM parameters in any way that you desire, however it is always wise to keep the following best practices in mind when building our your URLs for a campaign:
Consistency is key – by using the same naming convention for utm_source, utm_medium, and utm_campaign throughout your campaign, we can be confident that our clients data will be well organised when it reaches Google Analytics - UTM builders can help with maintain consistency.
Use lowercase parameters – If you use mixed case, Google Analytics will pull your data into different sources from the standard ones set within the software.
Google Analytics can clean your UTM data, but require additional configuration to set this up.
Don’t use spaces – While any URL builder will correctly convert your options into a neatly formatted URL format, eliminating spaces makes it easier to read - Replace spaces with dashes instead.
Use dashes not underscore – Underscores are often confused for spaces, so it’s best not to use them.