From my experience at Thorpe, I find the queue time boards to be generally inaccurate. I never really judge the queue by the time, but through the length now. Just from the last time I was at Thorpe, Inferno stated 15 mins for the last hour when we were staying in our seats, walk on. Rush was on 25 mins all afternoon, it was no more than 10. Saw stated 30 mins, look round the corner to find it's walk on.
It's something I think they need to work on, updating queue times. I personally have never seen anyone update them on tablets, I just assumed it was down to the ride team to update them.