How to know when OpenGL is done ?

Hello,

My basic question is:

How to know when OpenGL is done ?

So far the only thing I have seen is glFinish which blocks until opengl is
done.

However this website says not to use that:

http://www.opengl.org/wiki/Common_Mistakes

I have also seen glFlush but it doesn't seem to block... at least the
documentation doesn't mention it ?

My basic opengl loop will look something like:

for i:=0 to 1000 do
begin
Draw;
end;

The draw method depends on previous round results like frame buffer objects,
render to texture etc...

Therefore I think I should call glFinish() to be sure that the previous
round completed fully...

Is this really necessary ? (Does it have any drawbacks ?)

Are there other ways ? (Do these offer any adventages ?)

Bye,
Skybuck.