Thanks for such a fast response everyone,
The advantage of separating charging across more than one USB block is that if you use a single block the power is shared between all ports that are in use (sorry for the use of the word port for a cruise post), So a 40 Watt USB plug with 4 ports on it would give 10 W per port if all ports were in use. If I used 2 USB plugs and have 2 devices on one and 2 devices on the other, more power goes to each port and speed up charging.
I was thinking of a USB A block for things that can take their time and a USB C adapter for fast charging.
With 3 sockets, I will have to be a little creative and work out what can be charged when. Probably some kind of rotation.... ok I am getting too technical, this is meant to be a vacation. Ah well I will just chuck a load of things in to the case and use them as and when.