We have tests probably every 2-1/2 months at our club, and there are a variety of other clubs that we could likely go to. (Yes, we're spoilt; the Canadian system has some advantages). If you go outside of club, it's quite pricey.
We can't wait until summer; if tests are required, then, you have to get them done and waiting until a later test day and risking not having the pass done by deadline date is not a good idea. Plus, we want the tests done when they are ready: the cost of having a coach continuing to drill the test when it's ready, and not moving on to the next stage, bothers me in terms of cost-effectiveness.
Our tests start during the day ... they run to around 9:30 ... the general rule is go to school, leave before the test, and go back after, if at all possible. As your test days are scheduled well in advance, we work it out ahead with teachers. Now that my one kid has passed essentially every test that can be done in the Canadian system, barring some dances ... it's less of a problem ...