I like this. But there’s a but. We are allowed up to 20k pa in the ISA. Imagine I deposit 5K in the ISA this financial year. I have 15k left to use. Fast forward a couple of weeks. I transfer 2k from my ISA to my GIA. I still have 15k left in my ISA.
The point is that I find it very useful to be able to transfer from the GIA to the ISA. Not so much the other way around.