SLA KPI with custom duration

Dear community,

I have a requirement for setting a custom duration for KPI's for a given SLA, as follows:

- 12h

- 120h

- 480h

- 720h 

CRM offers to set actions in KPIs for the fixed time ranges, which goes up to from minutes, to 1 hour, later it increases 30 mintues each time, all the way to 8h and the next available range after is 1 day, 2 days, 3 days, and it ends here. Is there an option to set in more flexible fashion?

Thank you,

Piotr