One psychic told me that she thought free will only played a role in changing things about 2% of the time.  None of her predictions came to pass for me though.  
They always have excuses, I've probably heard them all by now..."dwelling" yes that's a classic that has been lobbed at me a few times.  Well I don't know how I'm not supposed to dwell on something when they have told me something it is just about impossible not to dwell on.
I also think if the timing is way off, then in most cases the prediction is just wrong, period.  I have never been a stickler for timing, so if they say 2 weeks, I'd still give them credit if it was 2 months.  But a year, probably not, especially not when they just keep dragging out the timelines longer and longer as you go along.