I think there is some ambiguous terminology here.
The Lyco engine has a gear pump for the oil. This means the volume flow rate is proportional to the RPM.
This is no good for lubing the engine, which needs a relatively constant supply of oil over the operating rev range, and a constant volume feed would just give you a massively high oil pressure at anywhere near operating revs.
So one has the pressure regulator valve which is a spring loaded thingy which controls the pressure at that point in the oil system.
At any RPM significantly above idle, this valve is partially open and is regulating the pressure.
The actual oil pressure varies around the engine and will be according to how knackered the engine is. A worn out engine will offer less resistance to oil flow (through the various bearing surfaces).
Also, the point where the pressure gauge is fed from varies according to the engine.