What does 'in general' mean?

[ElGatos]

Test No. incompl/advan-59 "Venus", question 9

Invitations were sent out and in ......... the response was quite good.

(a) all
(b) general
(c) common
(d) ordinary

Test No. incompl/advan-59 "Venus", answer 9

Invitations were sent out and in general the response was quite good.

Correct answer: (b) general

Your answer was: incorrect
Invitations were sent out and in all the response was quite good.
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Why is it not possible to say "in all"?

[Alan]

In all can't really stand on its own and would have to be completed as the following for example: in all cases ...., which then changes the meaning because in general simply means most of the time/generally.
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English as a Second Language
You can read my ESL story Present Simple

[Ceo Neeraj]

Hi Alan,

This reminded me of Pink floyd's song's lyric "...all in all its just another brick in the wall".
Is this usage correct here.
Please correct me if I have missed something here.

Regards.
CEO