I am sure I have said this before but.........
Scottish Power take (or in my case up until yesterday did take) regular readings from my smart meter, BUT they don't update your account at the same time, they only do that once a quarter.
However........ if YOU submit readings on line (like we have always done) that forces their computer system into updating your account. I have no idea if BG etc operate in the same way, but it's worth checking!
Like I said I have just switched to Octopus because I have solar panels and I am having batteries installed in a couple of weeks to make best use of both. I am happy to remain slightly in credit over the year. Previously with Scottish Power my dual fuel DD was £100 per month (we are careful with our usage, there's just the 2 of us in a modernish 3 bed semi with loads of insulation etc) so I reckon shortly my energy costs will be neutral, especially as I also get a FIT payment for the electricity I generate, even if I use (or shortly save) it.