Marketo often disrupts our sales team when they are on the phone qualifying a lead and editing that lead's record in Salesforce. If they wait too long before clicking "save", they get an error that the Marketo Sync user modified the lead record during their edit session and they lose their updates/ notes.
An important thing to note is that we do not use Marketo forms. We have a custom signup form our site which goes directly via API to Salesforce and then Marketo syncs with Salesforce from there.
Due to how our sales process and signup funnel is structured, we are considering changing the sync time between Marketo <> Salesforce to be longer than 5 minutes (reps can be on the phone with a lead while editing that lead's record anywhere from a few minutes to 45 minutes).
If you've extended the sync interval time between Marketo and Salesforce, did you experience any unforeseen problems? I'm currently doing a full audit to determine what exactly will be impacted if we change our sync time, but it would be really helpful to hear from anyone who has actually extended their sync time.
There is no real problem with this, except that you increase the risk of conflicting update on both sides. Note that doing this it will not completely solve your problem, only reduce it. Let say the sync is set to 30 minutes and starts at 9:00 and 9:30. If a sales starts editing a lead at 9:28, you will still hit the same error message.
I would rather use some alternatives, such as providing another custom object in SFDC and let the sales edit this object, to log the call, then, when this object is saved, push the updates to the lead (This could be done simply with workflows or using a flow for the user interface).