Checkout times suit individual circumstances (4,2,4)

I believe the answer is:

case by case

'individual circumstances' is the definition.

'checkout times suit' is the wordplay.
'checkout' becomes 'case' (as in the phrase 'casing the joint').
'times' becomes 'by' (I've seen this in other clues).
'suit' becomes 'case' ('case' can be a synonym of 'suit').
'case'+'by'+'case'='CASE-BY-CASE'

I've seen this clue in The Guardian.

Want a hint initially instead of a full solution? Install my app