OK, now I am able to see the valve’s datasheet, it DOES look like your valve has a lower holding current than typical ones we’ve seen. Yours has a holding current of 91mA (vs. 250mA typical), and inrush current of 290mA (vs. 600mA typical). So it’s about a third of traditional valves. I guess that explains putting all 7 wires into one port works for you. Well I still think it’s a bit risky to put all 7 in one port, but if you can do with 4 zones in one port, that should be relatively safe.
Yes, using a higher current rating transformer means you can run multiple zones at the same time, but not all inserted into one single port. It’s similar to say your house may have a electric panel of 200A, but each individual power socket usually only drives up to 15A. You don’t insert all appliances into one single socket.
I did think about the possible new feature of ‘virtual zones’ where a virtual zone means it maps to several physical zones simultaneously. This is relatively easy to do in firmware, but it will involve some amount of UI work. I will have some free time in the summer and will consider implementing this as a new feature.