So, in my view you'll need to use the lookup approach, having a table like that:
client, date_wday, date_hour, SLA
clientA, monday, 1, 2
clientA, , 2, 2
(...)
clientB, , 8, 4
After the lookup you'll have the SLA column for each event, where you can use a eval to define if the ticket met the SLA or not... could of IFs or CASEs.
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