As a general guide, the 80/20 approach is the ratio applied to your workouts, not the time spent in any particular training intensity zone or %ftp whatever.

Basically, if you do 5 bike workouts, make 4 of them easy and one of them hard. Hard can mean focussed on intensity.. e.g. interval-based. Same with run.

Swimming.. who knows. Swimming is weird.

Hope that makes sense, Rich.

Strict 80/20 would actually result in a lot of intensity if applied to hours- So to keep it easy on yourself- Go hard 2 days a week, then go pretty easy on other days.

You mean running?

As zedzded alludes to, this is very sport specific. You can get away with a lot more intensity on the bike than you can do with running and a lot of people say you should be doing nothing but intensity in the pool!

I'd say another important factor is your training breakdown at the moment. How much volume are you doing as it is?

If you're talking about running workouts and you're doing fewer than 5 sessions-per-week, I'd be focusing on how to raise the volume rather than worrying too much about the precise composition of interval sessions.