Hello kamil
A theoretical question of the first order.
You pose a difficult or impossible to answer question.
Here is my answer:
#1. If you are filthy rich, as often as you want. (Personal decision).
#2. If you are convinced in your mind, that it must be done. (Personal decision).
#3. If you have evidence that proves the need. (Judgment call).
#4. If your mechanic proves the need. (Professional advice).

__________________
ASE Master Mechanic

Prototype R&D/testing:
Thermal & Aerodynamic System Engineering (TASE) Senior vehicle instrumentation technician.
Noise Vibration and Harshness (NVH).
Dynamometer.
Heat exchanger durability.
HV-A/C Climate Control.
Vehicle build.
Fleet Durability
Technical Quality Auditor.
Automotive Technical Writer

1985 300SD
1983 300D

https://www.boldegoist.com/