I don't normally have a problem with it. That's not saying I don't care about the timeframe of books, that's just saying that most of the time if it matters, the author will put in some way to gauge how much time has passed, even if it's just a sentence or two. As far as I know (and I just re-read Elantris a couple nights ago), BS has done that in both Elantris and Mistborn.
In Elantris, the best gauge that I remember was about in the middle-end of the book. Sarene (while she's an 'Elantrian') asks Spirit how long he's been in Elantris. He lies and says a year. She thinks he's telling the truth, because it takes a while to plan a takeover like he did, and it's only been going on for a couple months (at most). But we know he started taking over almost right when he got in there....And from the time when Sarene leaves Elantris to the fight at Teod, it's only about a month. Maybe.
And in Mistborn, you learn the timeframe similarly--through the details. I'm pretty sure Vin says somewhere that it takes 5-6 months from when she got in the crew to the first Venture Ball. After that, she gets injured, and she's out for a good 2 months at least. And then the frequency of the balls--aren't they every two weeks? Or is it one week?--plus all the other little references to time--how long it takes to travel between Luthadel and the caverns, how long after the last ball that things start to pick up, how long Kell is gone at the mines, how long after Kell's death that they find OreSeur, and everything else--and you start getting a pretty good sense of the timeframe--about a year.