Tesco now state clearly on their information pages for CV-19 that they are limiting customers to 1 slot per week. So if you have just booked a slot you will be unable to see a new one to bid for for several days.
In theory this seems fair. One slot per week is surely enough for even a family if you choose carefully.
However in practice there is no guarantee that you will be able to secure a fresh slot even when you do bid. So the best most people can hope for is possibly a slot every 2/3 weeks.
Its also clear to me (from communicating to other customers who have newer accounts) that whereas I can see potential slots to the 19th May, others can only potentially book upto the 11th May. In other words, some customers are being shown potential extra slots to bid on. My guess would be those who are on the priority list and those who are on Tesco delivery saver plans who have paid in advance.
Tesco is a business and will not want to alienate its long standing customers. I run a business myself and understand the importance of being fair to regular clients and not taking them for granted. This is a lesson which many companies have yet to learn.
Whereas in the past Tesco released their new slots at midnight this has now begun to vary. They don't want their site crashing because every man and his dog are trying to log on at the same time. I have secured new slots in the early morning hours when whole tranches have been released. As a "night-owl" I can be at my computer until 3-4 am but obviously many people cannot.
Even when the slots do appear you have to be quick thinking and very "fast on the draw" with the mousie at hitting that little spot on the screen.
In other words folks it is a "game" with rules that can be manipulated.