When it comes to learning and perfecting a skill, constantly varied, high-intensity raining doesn't work. You may be able to use sheer grit and hard work to develop strength or work capacity, but that strategy is a recipe for failure when refining a skill. You will probably end up reinforcing bad habits.

A number of peer reviewed studies concluded that...

The body does not have the capacity to learn movement patterns when highly stressed/fatigued. To learn skilled movement patterns that are to be executed under fatigued conditions, that learning has to occur in non-fatigued states.

It's always preferred to learn new skills at the beginning of a session. It's also best to train them in isolation at first. Once you have become proficient with the skill, you can begin to add complexity. Here is an example of how you could progress cleans:

Level 1 = Clean technique work on its own

Level 2 = Cleans paired with a monostructural movement (i.e., EMOM of cleans and biking)

Level 3 = Cleans paired with an antagonist movement (i.e., cleans and push-ups)

Level 4 = Cleans paired with an agonist movement (i.e., cleans and wall balls)

Level 5 = Cleans in a traditional CrossFit metcon (i.e., cleans with muscle-ups and rowing)

To avoid fatigue, train your skills at low loads with no more than two to three reps. You can still get plenty of practice of the skill. You will just have to add a lot more sets.

For example:

Every 60s x 20 sets: 1 Slow Pull Clean @ 60-65%

With this setup, you accumulate 20 cleans at a low load and fully recover between reps. To make the session even more effective, film your first and last set and try to make them look the same before progressing in load or complexity in your next workout.