I've done the every 5 min additions before, but never precise or increased in amount. Usually I do something like [email protected]
, [email protected]
and 8-10oz split up equally every 5 min until the end of boil.
In my primary I have a IPA that I only used 2oz @ 60 and 14oz in the remaining 15 min of boil(IIRC). That might be more like what your suggesting.