I don't have scientific facts, but I can tell you what works for me. I do my strength training in blocks. This year, April/Maywere my strength phase. I maximized my strength training and maintained my aerobic capacity and slowly build my base. So run/bike at L1/L2 for 30-60 mins at a time. June/July/Aug/ were aerobic build phases and conversion of strength gains into real useable strength. So started short intervals once every 10 days building to two interval sessions in Sept.
October will begin another strength phase while distance drops a bit. November begins a ramp up in volume and distance again with interval sessions reaching three a week in December.
So far it seems to work. I've reached new fitness heights every few months!