Position of bien

Question

Can you explain why it is ‘avec ça tout devrait bien aller’ rather than ‘Avec ça tout devrait aller bien’ The usual response to the question ‘ça va’ is ça va bien’ and not ‘ça bien va”

Céline Pickard · Accepted Answer

Bonjour Ian,
I understand your point with "Avec ça tout devrait aller bien" with regards to the lesson on Expressing how you are with aller (Greetings in French). However, in that context, it is not how people say/write it in French. It's far less idiomatic and less natural in an everyday conversation.
I hope this is helpful.
Bonne journée !

Maarten Kamp · Answer

Ian, 
‘ Devoir’ is a semi-auxiliary verb here and the  ‘compound ‘ verb is ‘ devrait aller ‘.  
Basically, the rule here is the same as positioning of adverbs with compound tenses, the difference being that in this case most adverbs, including bien, are placed between the auxiliary and before the infinitive ( rather than before a past participle as in compound tenses). 
 https://www.lawlessfrench.com/grammar/adverb-position/
 https://progress.lawlessfrench.com/revision/grammar/where-to-place-adverbs-with-verbs-in-compound-tenses