What are your tagging and reporting best practices for bulk A/B Testing?

Hello MKTO Community,

I'm writing because I'd like to know how do you tag your emails and landing pages in bulk to report on A/B testing?

I know you can leverage email programs, but those seem to mostly be for one-off A/B tests.

Do you manually tag subject lines, CTAs and body copy with GA UTM parameters using the term or content tag to distinguish green buttons and orange buttons?

Do you keep track of them in an Excel spreadsheet or a specific Marketo report?

Do you leverage tokens to report out on subject lines that use your brand vs subject lines that don't? For subject lines that use free vs the word complimentary?

If you recommend a third-party software, I'd love to hear that too.

Any feedback and insights would be greatly appreciated:)

-Andrew