I have some training as a VFR pilot (for ultralight aircraft). I was under the impression that true north was always used everywhere (maps mainly), and adjusted

I have some training as a VFR pilot (for ultralight aircraft). I was under the impression that true north was always used everywhere (maps mainly), and adjusted with the local (and current) magnetic deviation when preparing the flight plan, to be able to take accurate bearings. Using magnetic north in maps and databases seems... misguided. Not updating instruments with the latest value too, although it must be a lot more complex to do so over long flights, with non-negligible deviation changes. Don't lose your bearings! I can imagine it's easy to rely too much on instruments when they're available.