The phrase "all the occasions when" is correct and usable in written English.
It can be used to refer to every instance or event in which something occurs or is relevant.
Example: "I remember all the occasions when we went hiking together and enjoyed the beautiful scenery."
Alternatives: "every time that" or "all instances in which".
Participating GPs indicated overall support for referral guidelines, but most appeared to use them in an educational capacity and very few (<3%) reported use on most or all of the occasions when a referral decision was made.
We atheists parade our inability to "get it" so loudly and often that people assume we are all tone deaf even on the occasions when we hear all too well.
But, on the occasions when all the men were summoned to a gathering, the miners embraced and told stories as if none of them had ever said an untoward word about another.
So it's essential to learn the 12 times table, for all those occasions when you slip through a space-time vortex and find yourself working on a farm in 16th-century Dorset.
All those occasions when people popped over to my house unexpectedly and I apologized for the mess claiming I was in the midst of giant reorganization project?
Given all the previous occasions when delays in resolving standards wars had opened the gate for new technologies to leapfrog existing ones, Time Warner should have known better.
LAHOUSEN: Yes, in all cases and on all occasions when his actual deputy-namely, Colonel Pieckenbrock-was not present, or when Canaris, for one reason or another, considered it necessary or advisable to have me appear as his representative.
However, at the outset of the study, all couples described occasions when the person with dementia had gotten lost while he/she was alone outdoors.
As vice-chancellor, Papen claimed the right to be present on all occasions when the chancellor saw the president, and, as Reich commissioner for Prussia, he controlled the principal administrative machine in Germany.
