Iterate, Iterate, Iterate
The process of making cards of magic is iterative. From each card throughout the final set there is a lot of iteration. This applies to anything, not just magic cards. There is the first draft and even many many drafts aren't going to make it perfect. Maybe close to perfection. But is perfection really a thing? They make a schedule and make cards to be released in that set schedule. This means that there isn't infinite time to make cards and this is mostly a good thing.
I can say that this is really applicable to life itself. If you ever studied for exams of any kind, you probably felt the need to iterate. In this case, to iterate means that you aren't going to read and solve exam questions once. There is revision, going back to read again, improving your speed, improving your essays. All that is iteration. I've read some books in psychology, self development and related fields and iteration means to admit failures. You ought to fail to improve. There is no other way and some personality disorders are disorders because one of the core issues behind them is precisely the inability to learn from mistakes. On the other hand, improvement is not just about doing good. It can also mean doing better at crimes, fraud, scams, etc. The world is not a fairy tale and in the same way some strive to be better for good, some people or companies strive to be better at doing bad things. As a piece of wisdom, be aware that if you fail to improve, somebody else is going to succeed. By that I mean that if your game or level design fails, somebody else is going to learn from it. Why can't that somebody else be you? Unfortunately I can't provide an answer for the question "When is enough, enough?". I can only say that the obsession with perfection is harmful.
About the schedule I can safely state that everyone should have schedules. If in one extreme there are those who are obsessed with schedules, perfection and this is really harmful for life. In the other end we have people who are unable to follow schedules and the absence of schedules, deadlines or any form of control or organization is also harmful. I firmly believe that an universal recipe to tackle this does not exist and never will. There are just too many variables to think in one universal solution here.
Game design and level design are very much about iteration. If you ever watched a documentary about making movies, games, levels. It's an iterative process. Don't expect a plan to be perfect and then following it without any hiccups, bumps or failures. No, it's impossible to foresee everything. You have to be all ears for feedback.
