Yes, Sundays and holidays are not to his liking.
'Tis because there is no mail delivery on those days.
My lovely dog is crazy about our regular Letter Carrier.
The mail usually arrives mid to late afternoon at which time I am often to be found on my Lanai reading a good book.
The letter carrier (Sh-ane) first delivers mail on a street which is roughly parallel to mine, but on the other side of our lovely retention pond.
Zi-Zi (Zion) recognizes the sound of his van and becomes alert, even more when he sees the van (across the pond, some three hundred yards away).
That's our signal to go outside. I know that the mail will arrive in about five to eight minutes.
We wait. Zion holds his head up high.
When the mail van gets near I let Zi-Zi off the leash and he bounds forward ready to greet my letter carrier, not only to get a treat, but also because he is is entirely fond of Sh-ne, and Sh-ane of him.
I may have posted about this before.
Forgetting which here are a couple of pictures of today's Zion and Sh-ne encounters
Fabulous Dog. Great Letter Carrier.