Imi,
As oil heats up it grows in volume.. that's what the viscosity improvers do, try to make it thicker as it thins out.
If you have a car that at maximum on the dipstick is 7 litres, and have 6 litres of oil in the sump when its cold & has been sat all night.... then heat it up to normal operating temp and it becomes 7 with the engine off, you have the correct level when its hot (because engines run with hot oil).
If you have 7 litres when its cold (i.e. set it to maximum when cold), then heat it up & it becomes 8+ litres this will obviously be too much & may cause leaks, power loss etc
If you have 7 litres cold just after running the engine for a few seconds; with the large amount of oil hang up in the upper parts of the engine caused by the slow return of oil to the sump as it is very thick, you may end up with 9 litres when checked properly. This is 2 litres over spec & is likely to blow a seal (especially in turbo engines where crank case pressures are higher then NA).
If it is set to Max level hot after 5 mins, you'll find that when stone cold it will be about 5mm lower on the dipstick. This is the room for expansion! So when doing an oil change, fill it up with the new oil to about 5mm below max after running for a few seconds to check for leaks.