That drives me crazy too George. Common sense is unfortunately uncommon these days..

We may take longer on a ball if there's a lot open, but if it starts to fill up, we'll leave once our 90 minutes is up or if we're done sooner.

I think there are some places where there are exceptions - such as the baths. If you hike the baths and go have lunch or breakfast at the top, you will likely be closer to two hours. I think its fine as long as you don't take an excessive amount. This is why we always visit from Leverick now too.