Being a Brit I can honestly say the last thing I would ever do is not take any of my allotted holiday. Its just not happening. I don't think I have ever even known anyone who doesn't use theirs. For instance after my summer break I now have 6 days left - I'll plan when to use them and book them over the remainder of the year rather than keeping them 'in case' and being stuck with them. I'd like to say I return refreshed but I return probably more snarlingly irritated than before. Sorry colleagues. I do enjoy my job plenty but actually find it easier when I'm settled into a steady routine of doing it. Who's to say I wouldn't be worse without the break though, and I might have more energy subsequently.