RE: hiit or aerobic in bulk.-add your way
Like Mstar said getting a feel for what works for yourself is best.
I now combine HIIT and normal C.V. on non weight training days. 40 minute total on three machines eg, bike, row, run and stick a six minute HIIT session in the middle. I like the way the HIIT makes me feel later in the day but if I had a twenty minutes plus of it to look forward to I would dread it.