I am not very good in expressing any deeper thoughts as I am no English speaker, but I would like to get some discussion on General Tilney´s character going. So here is my humble attempt:

The General seems to be a man of action. In ch.22 he kind of reveals his basic principle:"I am sure your father, Miss Morland, would agree with me in thinking it expedient to give every young man some employment. The money is nothing, it is not an object, but employment is the thing." This is supported by his confession in the garden: If he had a hobby–horse, it was that. He loved a garden. His pamphlet-reading habbit while others are sleeping also fits in very well.

This might be the reason for his strong inclination for punctuality. Not only does Eleanor inform Catherine that the strictest punctuality to the family hours would be expected at Northanger (ch.20). We already observed that inclination in Bath:

ch.12: "...my father...being hurried for time...made a point of her (Eleanor) being denied."
ch.20: The bustle of going was not pleasant. The clock struck ten...and the general had fixed to be out of Milsom Street by that hour.

What struck me in that context is an apparently minor incident in ch.12 - the Tilneys arrive late for the theatre! On the beginning of the fifth (act), however, the sudden view of Mr. Henry Tilney and his father, joining a party in the opposite box... Now that doesn´t seem to fit in. But after some consideration I came to the conclusion that it does fit actually. Doesn´t it reveal the General´s attitude towards work and leisure? Everything that is important to him has to be done at once. But going to the theatre seems to be of secondary importance. So he obviously has no difficulties to arrive too late here...

Hm, while writing this, another thought comes to my mind: Perhaps that´s another example of the General´s self-conradiction. He wants others to believe that he is punctual, but if you take a closer look, you realize that he doesn´t live up to his own standards: He leaves Bath being too late and he even arrives much too late to the theatre!