A couple weeks back, there was this blog post:

https://dataswamp.org/~solene/2022-07-01-oldcomputerchallenge-v2-rtc.html

tl;dr:

Use the internet (a bit) like it was in the 90'ies, i.e. only connect
for very brief amounts of time. I think 20 minutes a day was already
quite a lot for us. It would be total madness to also limit the
available bandwidth to the speed of a 2400 baud modem (or even a 56k
one), so that's not part of the experiment.

(I've never heard the term "RTC modem", though. It was known as "dialup
internet" to me.)

I'm going to try this experiment in the near future. First, it's always
fun to indulge in a bit of nostalgia; second, it's a good opportunity to
reflect on how I spend my time. What am I doing online all the time? Do
I actually need to be online?

Not sure yet if I'm going to allow Netflix or not. Yes, it's an online
service, but it's just "watching movies". It's not like we didn't do
that back in the day, it was just called "television". So I'm inclined
to declare "Netflix = TV".

The actual time accounting should be rather easy in my case. I only use
one main machine, so I can just track if dhcpcd is running or not.