You are opening a support case and you need to set a priority level, but which one do you choose? Here is my personal take on what the priority levels mean.
Let's imagine your Marketo is a person who isn't feeling well, so you have decided they need medical attention. Here are your priority levels.
P3 - We need to go to the doctor.
P2 - We need to go to the emergency room.
P1 - Oh god, someone call an ambulance!
So when you are opening a case, ask yourself "Do I really need an ambulance for this Marketo issue? Do I need to go to the emergency room or will a regular doctor's visit do?"
Now if someone called an ambulance for a bad stomach ache, you might think they are over-reacting. Surely a visit to the emergency room would do just fine, right? And if someone is routinely going to the emergency room, you would think they are either a hypochondriac, or they have some underlying serious health issues that need to be addressed. With this in mind, if you are routinely opening P2 cases, you may want to consider whether your issue warrants a trip to the ER, or you may want to look into addressing the root cause of the Marketo health issues that keep arising. And just like a doctor would rather get you healthy in the long run, I would be happy to help you, in my capacity as Marketo Support, resolve the base issue rather than treat the symptoms.