What you experienced was life—the randomness of it. 

For someone who has found new value in deploying checklists and protocols, this randomness can be unsettling. You might deploy a protocol to address an unforeseen complication presented by the randomness, only to find that it fails. Deploy another, and find that it fails as well. 

What tends to follow, among other things, is frustration, anxiety, confusion, and/or an unconscious pushback against applying effort towards making progress. 

Take, for example, the sense you might take into a new day - say, Monday - that your "Today's Priorities" list will facilitate focus. Only to find, in using it, that you experience resistance against applying the effort needed to make progress. And only after hours, maybe even days of reflection, do you come to the realization that the constrained and hierarchical nature of the (24-hours bound) list, coupled with interruptions delivered by randomness, imposes limitations that, rather than curbing resistance, feeds it and stifles your drive to apply effort. 

What works, at such moments, when looking at problems through the lens of checklists and protocols, isn't forced adaptation to the constraints of a tool or protocol, but rather an approach where generating (and documentating) steps necessary to arrive at desired outcomes guides. The value of checklists and protocols resides not only in their utility as repositories for easy recall of solutions but also in the opportunity they provide to allow the creation of paths and flows for when you come upon new situations. 

A helpful heuristic is:

This is valuable because of the freedom it offers. You are not constrained by any system. Every system can be subjected to revision. 

A "Today's Priorities" list for dealing with a Monday, from the example, might bring resistance into effect because it is being misapplied. The approach might be best served if the Today's Priorities list for facilitating focus isn't used as a tool strictly for building momemtum. Momentum might be achieved with a list free of all the limitation of a "Today's Priorities" list. The flexibility to apply tweaks to optimize your approach resides in the opportunity checklists and protocols provide.

The unexpected is bound to arrive as a result of life's randomness. Your response is to tap into the freedom you have to design flows that allow you to move through it.