We tend to think of running as a master planned, top-down process. We set the training plan, get out the door to execute this plan, run races that are on the plan, etc. But as we invariably make adjustments, we constantly put those adjustments back into the context of the master plan, so that everything makes sense from the level of a single day's run all the way up to the several month vision. In other words, we have to justify all of the small actions through the grand vision and it all has to be consistent, with definied physiologic goals for every little piece of the training and racing puzzle (i.e. so that coaches feel good about it).
This process makes some sense in that we have to update the rest of our running world given this new information. Without doing it, we would overtrain, get injured (even more than otherwise), and a whole list of nastiness would ensue. Top-down master planning also makes sense because it is what gives coaches and the people who write training plans some credibility. If reality was so far removed from what the coach wrote down, that wouldn't look very good.
However, I don't think that this process of needing to have an up-to-date grand vision in order to justify every little micro-decision is necessary, useful, or what actually happens in real life.
Instead, a more useful framework is to think of training as a series of decisions. These decisions span from the micro-level (I'm running too fast right now and should slow down a little) to the macro-level (I want to focus on ultras instead of the mile). There is a continuous stream of decisions being made and at certain points in this stream, it makes sense to consult your coach or your training plan. That coach, too, makes a decision in how to best consult at the moment.
While this new framing might seem subtle, it does have impact on what you actually do in the moment.
In the military, the concept of Commander's Intent is extremely important. The idea is that during the heat of battle, the commander cannot make every decision, so it is imperative that all individuals have sufficient information to make their own micro- decisions in the absence of the commander. This practice has been transformative, as now missions can be successful even in situations where things go very much not according to plan.
In running, a similar situation exists. Sure, you might get a recipe for a workout from your coach, but the coach doesn't know the full context of your run and cannot make adjustments on the fly. It is just a best-guess stimulus. This means that it is up to you during the workout to dial in the right effort. The coach can convey what the workout should feel like so that you can make the decisions about how to adjust effort without the coach. If the coach just gave goal splits for a workout, sure, you can adjust to the split times, but that might not actually be the "commander's" intent here as those splits might not be reflective of the effort that you are putting in.
The Commander's Intent case illustrates how a goal on the training plan manifests itself in decisions. On every level of the training hierarchy, from a single run to a five year vision, decisions are made. Whether it is concious or not, these decisions are made according to some ranked list of what is important. In practice, many times, these decisions are ad hoc and inconsistent - this is not ideal as it means that there is an impediment (likely to do with someone's ego) getting in the way of clear thinking.
In this framing, there is a hierarchy of principles shared between the coach and athlete. Every decision made by both the coach and athlete IDEALLY should be consistent with this list. For example, without common principles, an athlete might feel his/her achilles flare up during a run and think, "no problem, I'll just run through it." This might work out or might be a really bad decision, and thus illustrates a situation in which we really should have essentially made this decision beforehand so that ego cannot get in the way. If the athlete and coach had "Staying healthy" as a very highly-ranked principle, in the moment, the athlete can now think "Staying healthy is ranked higher as a principle than maintaining high volume so I should pull the plug and play it safe." In fact, the athlete isn't even really having to make the decision - he/she is just consulting the list where the decisions have already been made!
This framing does not imply that an ideal coach is just a robot - actually the opposite. The coach is necessary to be the outside observer that has an effective communication channel with the athlete, ensuring that decisions are being made according to the principles. He/she must understand the athlete and the ways in which the athlete tends to deviate from the principles in order to "right the ship." Similarly, the principles guide the coach in an environment of great uncertainty to make better decisions.
Let me be clear that I'm not saying that planning is bad. I'm just saying that plans are insufficient guides to make the best adjustments in the moment. And given the uncertainty associated with prescriptions that coaches dish out, these adjustments are precisely what bridges the gap between uncertainty in the plan and reality. In other words, they are CRITICAL for the coach and the athlete to get the desired stimulus. Only by understanding what is important can an athlete make on-the-fly adjustments reflective of the Coach's intent.
This idea of using principles in decision-making was of course made famous by Ray Dalio in his book Principles, but has also been applied in a running context to the management of team culture. I really see value in using it to guide training, so more to come on this topic.