At my job I rarely get to influence the design of our sites, but it is something I enjoyed when I worked freelance.
Talk to the designers. This should be a natural part of your job (read: collaboration) anyway, but deliberately ask questions; try to get them talking. This can be relationship dependent, some designers are touchy and you may have to establish some rapport first, but many designer enjoy a friendly challenge to their decisions. Don't be combative and skeptical, present questions which respect their ideas, but gets them talking and perhaps re-thinking what they thought. You may learn a lot in the process. You may not learn PhotoShop this way, but that's rather secondary to design talent anyway.
Talk to everyone for that matter. Without going on too much of a tangent from your original question, website products are only as good as the collaboration of people producing it. You're little more than an ant in this vast world of complexity. How much does a single ant ever accomplish?
I was wondering how you guys and girls stay on top of your skillset outside of work?
If you're not being challenged to learn new things -or at least have the opportunity to be- in almost every project, you might work in an assembly line; find another job. Otherwise a tremendous amount of learning comes from the project itself. Find an excuse for a task to give you reason to explore. Ask yourself if you're pushing yourself beyond the norm, or if you're merely delivering a Xerox copy of what already exists in your head.
That strategy is important, because nearly everyone is too consumed by pressure and too ready to live their normal lives by the time "the project" releases their psyche from its grasp. We're all a little bit Pavlovian. Once the pants come off, the recliner is tilted and beer is in hand, there's not a lot more you're going to cram into your head that day. Learning generally needs to happen in the context of a project.
Curious as to your suggestions to learn new things without being burnt out.
How do you go as quickly as possible around a race track without crashing?... You don't. You either go too slow or you eventually crash. You may learn to balance things a little better, but inevitably, you get force-fed a few lessons the hard way.
This is why passion is always recommended before diving in. Passion is the heat you cook with, it's what wakes you up on the middle of the night with an urge to resolve a problem. It will eventually burn your brain, but you need it to move forward. Contrary to popular belief, the pursuit of money isn't interesting enough, and especially early in your career, won't be plentiful enough to tolerate the fried nerves and persistent knee-deep bullshit.
Also patience. It's like a real life RPG x100. You don't reach "master level" after 100 hours, it might take you 10 years. If you're starting to get overly concerned about your progression, perhaps its time to take a break.