I am aware that there are sections private, public, published...
As I several time had troubles, because an existing method was not reachable in code I did not write, - I never use this sections.
I cannot se an advantage for them?
If there is a good reason, why I shall to it, - I am willing to learn.
Well first of all: The top section (the one after class, without any marker) belongs to the IDE.
If you don't want the IDE to play with your code in unexpected ways, then use any other section.
Also that top section is "published" (at least in forms and similar). And that means it produces extra data, that goes into your final exe. But your code doesn't benefit from that data. So you just add extra bytes. (It's called RTTI...)
Otherwise you can put all you need into "Public".
But other section can provide peace of mind. Example.
You have a function
procedure ChangeInternalFlags;
If this is called by accident, all kind of odd and hard to trace side effects may arise.
And then you have
procedure SafelyChangeInternalFlags;
procedure RevertInternalFlags;
procedure UpdateInternalFlags;
Those have checks, and ensure that ChangeInternalFlags is only called when that is correct.
So only those 3 functions should be allowed to call ChangeInternalFlags. All other code must call one of those three.
Then you do want
ChangeInternalFlags
to be private (actually even "strict private")
that way the compiler will tell you if you accidentally try to call it from elsewhere.
I have in some cases even gone to the trouble of doing a nested structure, to protect the field even more... But that is a truly rare case.