This is probably a silly question:
Does a lead ever revert back to open status after becoming MQL if they're not followed up by a sales rep after a certain amount of time?
I don't believe it does, but looking for confirmation.
It depends on how your Lead Lifecycle is set-up in your Marketo instance. If not set-up, you can create a smart campaign to do so
Hi Mark! If a lead has made it to MQL, but isn't being followed up with, pushing records to a 'recycled' or 'nurture' status would be best so you can keep track of those that marketing deemed as qualified, but sales did not. This is useful information because you can start to create content as to why someone isn't moving forward, or understand what not to deem as marketing qualified in the future.
I don't believe there's documentation for that specifically, but I would recommend having a flow step in the MQL campaign that's wait step - this would be the amount of time needed to pass for the automatic MQL > Recycle move. The next flow step would listen for IF the status is still MQL after the given amount of time, then move to Recycle (and mark any other relevant lifecycle fields). Otherwise, do nothing, because this should assume that they've moved forward or manually been recycled.
Helpful additional documentation is here: Revenue Cycle Models - Marketo Docs - Product Documentation