An opportunity that far too many people don't take advantage of is the idea of a quarterly audit. Don't worry; it has nothing to do with your taxes. Instead, it's a process that you should go through a few times a year that provides you a chance to re-assess and re-evaluate. It's a time where you force yourself to stop and think "This print mailer was designed in January, and it worked great in January. It's April, now. What needs to change?"
When performing an audit of your print marketing materials, make a list of everything that has changed since the last time you had the chance to re-evaluate things. How have your business goals shifted in the last few months? Have you accomplished more or less than you thought you were going to at this point? What does your average customer look like today, as opposed to three months ago? How have your campaigns been performing?
If you can provide business-specific answers to questions like these, you create for yourself a valuable context that you can then use to make the right, actionable decisions regarding things like design and distribution moving forward. What you're doing is taking a process typically completed at the end of the year, looking backward and seeing what worked and what didn't, and then forcing yourself to do it as often as you can.
Another reason why the idea of the quarterly audit is so important is that, by and large, the world of print marketing is changing rapidly. New technologies, techniques, tips and best practices are emerging all the time. Taking the time to go back over everything you've done so far a few times a year gives you a chance to incorporate all of this into your workflow as soon as you can.
Think about it this way: maybe you designed new buyer personas in January with an aim towards attracting a different type of customer. You've produced everything with those buyer personas in mind, trying to maintain a consistent voice across all collateral. If things aren't working quite right and need some tweaking, would you rather know in April or wait until December?
In the end, what you're doing is strengthening your foundation. Many people use January 1 as a great chance for a "fresh start." It's a time where you stop and think about where you are, where you want to be, and how you're going to get there. If you do this multiple times per year, however, it puts you in a much better position to be responsive to both internal and external changing factors. Above all else, it's an opportunity to make sure that you're still headed down the path that was important to you on January 1, if that path is still important to you at all.