Book Tuesday to Thursday if museums are the reason for your May Europe city break. You will usually face shorter queues, more usable gallery time and less pressure to rush from one landmark to the next. The strongest plan is four nights in one city, with the biggest museum booked before lunch and the most popular attraction kept away from Saturday. That sounds simple until a public holiday, a timed ticket, a late-opening schedule or a non-refundable room turns a calm break into an expensive logistics exercise. This guide treats the trip like a budget decision: identify the scarce resource,…