I got sent an email about a week ago suggesting I booked my Tesco slot for Xmas. I booked mine then and I guess other people who got sent the email did too. I would definitely not have thought about doing so if I hadn't been prompted.
StarlightMcKenzie - not sure extra drivers would really help - they are not going to increase the number of vehicles for a few weeks of the year, and I do not know when their last or first deliveries are, but those hours are unlikely to be increased either.
Not sure many would want a delivery after 23:00, though years ago my OnDigital [forerunner of Freeview] box was replaced with a delivery at 22:45 so there have been delivery firms willing to run that late... but perhaps at some higher cost in salaries.
Having seen some recent thread about the slots being made available (primarily, it seemed to the most loyal customers, first) and promptly filled up, it hardly seems likely that this will improve in future years.
They were adding days for only particular accounts so individual users would see extra days when they could book a slot, and that does reflect a "reward loyalty" approach, even if they got it wrong for some "big spenders", who might not return to Tesco in future.
Will be much worse if the big 6 (Asda/ Co-Op/ Morrisons/ Ocado/ Sainsbury/ Tesco) swallow up any more chains. Tesco has approx 30% of market already and small firms must struggle each time a new Tesco Extra or Tesco Express opens up.