Do not seek mastery.
That is, do not try to buy mastery off a shelf. Also do not try to train mastery in the workshop alone. And definitely do not try to learn mastery from imitating the works of the greats.
Mastery is not a product or a process—that is, it is neither a product or a process as external object. Mastery requires a master. It is the master that makes mastery. What makes mastery is being able to go from sitting somewhere as they are to getting a result. The intermediate steps might include procuring materials, looking up references, putting together concepts, creating the initial work, polishing the output for display, and even knowing when to take breaks and eat meals. Mastery is not a portfolio, even though mastery naturally can generate a portfolio.
I think the different oral apprenticeship systems have something very wise to them when they get students to live with a teacher and spend practically all day within the teacher’s ecosystem, acting as a cog within an existing empire. At first they might only chop wood and carry water (if you know you know), but through observation and imitation will know enough rudimentary material to create some novice work. From there they graduate through the ranks of the live-in community and maybe even one day graduate to start a practice or tradition of their own. By then, they will have already learned everything about the life of the master, not at all divorced from all the social and material conditions necessary to creativity.
The oral apprenticeship system I am most interested in these days is the partimento tradition originating from the Neapolitan conservatories. The student, often an orphan not yet able to even read, was immersed into a daily curriculum with frequent practical exercises and then written work related directly to those practical exercises. They were even around peers who were going through the same experiences, and with whom they could have regular dialogue, either in words or in music or even in esoteric body language in-jokes (along the lines of imitating the funny motions of an awkward pedagogue). By the time they wrote their own music, they already muscle memorized enough figurations in their fingers and voices that they can spit out arias the way that you and I spin out stock greetings or go into our usual bits with friends. There is an element of off-the-cuff banter that is developed. We wake up, pray, eat, poop, and go to bed. Oh, and somewhere in there, we created meaningful work.
The productivity guru guys almost all end up talking about lifestyle points, because it is beyond obvious from a systems perspective that our work is an outgrowth of who we are. Good work does not fall out of the clouds, and it equally does not fall out of our hands in a vacuum. We need air to breathe, after all! We also need water to drink and splash on our faces. We also need sunlight, and exercise, and flourishing relationships. None of this can be divorced from the immediate technical considerations of work. After all, even though we might divide up creation into multiple parts and contexts, there is but one creation by one creator. That one true creator, God, is the highest master of them all.
Do not seek mastery. Seek to be a master.
And also, seek the highest master. But that much is obvious.