Isn't that somewhat normal though? Isn't it for the same reason a rule of thumb to have at least 3 ships in order to have a constant maritime presence?
That applies to another context. That rule is having 1/3 of the ships at the sea, 1/3 in the bases ready to deploy, and 1/3 in various types of maintenance or refits. This schedule enables you to have two-thirds of your fleet immediately deployable if the need arises. Since not all maintenance produces are complex or critical, most of the ships in maintenance should be deployable after a week of preparations too. With this schedule you have most of your fleet promptly available with good ship lifespan, your personnel not burnt out, your sailors getting enough training, and the ships not getting overused in peacetime.
Here, Britain is failing at that. They should have had at least one ship rapidly available. In several months of the year, they should have both ships available, especially if there is time to prepare. Here they couldn't get any of their aircraft carriers available despite attempting to. Both ships were supposedly available but they found mechanical problems in both of them.