Oh yes - very hard work. I reckon almost everything museum-wise that says 'will take approx. 2 hours' you need to leave 3 hours for or you really can't see it properly. And I reckon it is probably better to see less things properly than to see lots of things so quickly that you really didn't get much out of it apart from ticking it off as seen - if you see what I mean.

So, for example, the V&A is fabulous - but decide which bits you are interested in, and look at them, rather than trying to cover every inch of floor space!