Acids are a regular byproduct of the combustion process - but more than one of the additives in engine oil neutralises the acids and renders them relatively harmless.
However, that is IF, the acids have reached the oil.
Acids from combustion can be retained in the engine - but not necessarily in contact with the oil held in the crankcase.
I have seen big end and main bearings, and crankshaft journals, etched by acids - thus showing that acids do settle in parts of the engine in amounts that can do damage.
The best thing you can do with any component that relies on regular lubrication is to start it or move it on a regular basis, to ensure the oil is thrashed around and coats all the important surfaces.
The oil draining off the surfaces of crucial components such as camshafts and cam followers is definitely a major problem - and corrosion can often form on these surfaces in as little time as several weeks.