I don’t take manual meter readings as often as you suggest (no need IMO) but I do take them every month or two.
To be clear, I was mainly suggesting frequent (daily/weekly) for people who have no idea how much they are using right now. Once you know, then monthly, bi-monthly, quarterly is fine.
I'm not sure how a variable DD is less stressful? You're very much exaggerating how much "messing about" it takes to log into your account and enter the DD amount you want to pay.
I've seen people raging in here due to getting into DD wars with their supplier, having to keep contacting them to barter to change the values, being unable to adjust their DD to what they want to pay, cancelling DD so they can set it up again with the figures they want to pay etc.
That all sounds
far more stressful to me than just using variable DD and paying for what you consume. If you are in a financial position to be able to pay variable amounts that is.
I do appreciate that not everyone can do this, but if you can, it doesn't make sense not to.
So it's only beneficial to switch to usage-based billing in the run up to summer? If you switch to actual usage DD billing now you'll end up paying more over winter than flat-rate DDs would have been and lose out on the interest.
I don't know about you, but the tiny levels of interest my bank pays, this isn't really a concern one way or another.
I don't like having a huge debt or credit with the supplier, usage based has ups and downs, but you can see what your bill is after you put your meter readings in, and then you get charged so you can see what you're actually using as you go.