They are fed like a pressure bearing but have a significant leak out to onward feed the splash section generally.
The oil restriction "jets" are there to separate the high pressure crank assembly from the low pressure head demands and maintain correct pressure level for crank assembly.
The cam is obviously running half crank speed, the bearings are quite small diameter so surface speed between cam and head bearings is fairly small, making it fairly undemanding of oil pressure, as long as it gets a clean constant supply, then it's happy.
More of a constant feed than pressure for cam journals.
