Tank thermal loss

Now I’ve replaced my delay timer PCB and got the tank thermostat set just below the boiler output water temp (old oil boiler, max hot water temp was too close to the tank thermostat temp), the system is running more like it should be. Since doing this, with the heating turned off (e.g. overnight) I’ve observed that the boiler kicks in once an hour for 10 minutes each time, is this about right for typical thermal losses from the tank? If so, I’m probably going to install a timer on the boiler to shut it down overnight as 80 minutes of the boiler firing overnight doesn’t seem very efficient, pretty sure it would take much less firing each morning to get the tank up to temp. Thanks for any advice.

First test, turned boiler off last night at 10pm, turned it back on at 8am, boiler fired for 54 mins to get the tank up to temp. Had the system stayed on overnight the boiler would have fired for around 100 minutes, looks like a decent saving to be had by installing a timer to shut it down overnight. I'll test this manually over another few nights to check these numbers are reliable.

Just to close the loop on this, I've done some more calcs and it looks like switching the boiler/tank off overnight will give me a saving of around 17 - 20% on my fuel usage. This is based on the boiler consuming around 3 litres an hour (Camray 3 manual). Appreciate the system is now almost 25 years old but the tank thermal losses seem to me to be quite substantial.