I’m a french native and i think there is no fixed rules about that.

Normally, small adjective (beau, joli, sale, etc.) are before the noun, regardless of the complexity of the sentence.

But, I think it’s also guided by intution. We said blackboard: un tableau noir, even if noir is a small word.

It can be really complex, because the position of the adjectif have an incidence on its meaning.

For example:

Un homme grand => a tall man

Un grand homme => a great man

But, this is a special case for homme, femme ou personne. Un grand chat have the same meaning as un chat grand: a tall cat.

But other adjectives vary their meanings with all nouns.

ma propre chambre => my own room

ma chambre propre => my cleaned room

mon propre vélo => my own bike

mon vélo propre => my cleaned bike

Or

un sacré livre => a great book

un livre sacré => a sacred book

Moreover, the familiar verb form differs from the sustained written form.
For example, we said:

une habitude étrange, un repas succulent, un homme beau

but in a book, you will read more often:

une étrange habitude, un succulent repas, un bel homme.