If you aren't reading the cards for yourself...or even if you are, really...how often should you get a professional reading?
Well, there's definitely such a thing as too often. If events and cycles in your life haven't had time to progress, the tarot isn't going to have anything new to tell you. And trust me, no matter how often you ask, the tarot is never going to sacrifice the truth to tell you what you want to hear. Rewording the question, and asking again in a week is not going to help.
BUT, there kind of is such a thing as not often enough, too. Sort of.
You see, the tarot can only tell you so much in a single spread, and your reader is only going to be able to go through so many spreads in a single reading, so the tarot has to prioritize to make sure you get the info you need now. And that might mean blatantly ignoring your question about taking the job at the new company that just opened in favor of telling you that it's long past time for you to reconcile with your sibling and heal that relationship, or even vice versa.
You can come into your first tarot reading in years with a specific question...but know that you might not get it answered, and that's not because your reader isn't reading the cards right. If you want specific answers about specific issues, you'll likely need to plan on having a couple readings in a row done, so you can work through the stuff you've been missing, and get to the thing that you think is important.
And don't waste everybody's time by tuning out the first few readings, just waiting for the cards to start talking about something you care about. Until you start integrating the info the cards are giving you, they very well may not have much else to say. Of course, they'll give up sooner or later, but a tarot deck that's being ignored is going to develop a bad case of tarot snark at the least, and meaningless gobbledigook at the worst.
In order to avoid that tarot info traffic jam, I recommend getting readings about every three months. Giving it enough time for the seasons to change generally ensures you won't be going over stale old ground, but keeps it recent enough that you're still fairly up to date on your issues, and the issue that you think is important is what the tarot is going to think is most relevant, too. Of course, if something big happens just a few weeks after your last tarot reading, and you're left completely reeling, it's totally legitimate to book another reading, as long as that isn't the only thing you're doing to cope, learn, and move forward. Don't let the tarot become a crutch.
And in fact, before you book that next reading, take a look at the pictures/journals that resulted from your last reading. (Oh, are you not taking pictures of the spreads that come up at your readings, and journaling on them later? Clearly I'll be writing about that next...) If nothing in that past reading seemed to point to this event, you should e-mail or call your tarot reader, and ask her or him if the reading indicated anything like this. Your tarot reader should also have photos/journal entries regarding your reading, but you can always e-mail him or her yours if not.
Of course, it's entirely possible that your last tarot reading didn't indicate anything like this. The future is constantly changing, and how far the tarot is looking ahead is a direct function of how crucial the present situation is, and how big of an impact your present choices are likely to have on your future. If that's the case, then I'd say, yes: book anther reading. Figure out what the context is for this situation, and figure out how to make the most of it.
Other times I strongly recommend getting a reading are around New Year's. Choosing your card for the year is a great way to have a concise road map of the challenges you'll face, and the lessons you should be learning in the year ahead. I really find it indispensable. So much so, in fact, that if you are signed up for my newsletter (which you can do by clicking here), you'll receive a discount on your New Year's reading. So, you know, get on that.
Birthdays, as sort of a personal New Year's, are also a great time to get a reading done, and as such, tarot readings make awesome birthday gifts, and along those same lines, anniversary gifts for couples, looking to get a clear view of their relationship, and the lessons they should be learning and applying through their interactions with each other.
So, think about scheduling four tarot readings a year: one per season. If possible, have two of those readings coincide with the New Year, and your Birthday. If you're in a long term relationship, you can also think about scheduling one around your anniversary, if your partner is receptive to the idea. You can always throw in a couple extra for the year if circumstances warrant it, but if you're living a fairly uneventful life, four to six should really do you.
And if your tarot reader happens to be weird about you whipping out your cell phone for a picture of a spread before its cleared, or e-mailing him or her weeks or months after a reading to ask if a recent event or situation makes sense in the context of your last reading, you might want to consider switching to a reader more willing to help you make the most of your tarot. Like, you know, me...and I hope someday, yourself! :-D