What does “signature holidays” mean?

Question

I found this expression in a book but I don't understand what it means.

A man never takes vacations from work. Here's the complete sentence, with some more context:

She couldn't remember him [the owner of the garage] taking any time off. Because he had a garage to run, there was never an opportunity to shut it down except for signature holidays. Besides his customers’ vehicles, there was always something else that needed attention, or the accounting needed to be done, or one of his employees had called in sick. Since they had no savings account to fall back on, he was more inclined to do things that earned money instead of wasting it.

What does it mean? That he only closes for "official" holidays (i.e. Christmas, New Years' Eve...)? I found no help in dictionaries.

Answer 1

I don't think it is a normal usage. The closest definition for signature is:

2. adjective
   A signature item is typical of or associated with a particular person.
   Rabbit stew is one of chef Giancarlo Moeri's signature dishes.
   The dress reflects our signature style of understated elegance with individuality.

In your example, signature should refer back to the garage owner, not the holidays. For example:

The owner has a signature major repairs plan that saves you money.

I imagine the author meant "important/key holidays" or something like that.