Hmm, sounds like my hitherto-though-of-as-rubbish approach might actually be of use after all then!
I’ve got a SS on mine – and my entirely unscientific approach is: get on, stretch/warm up for a bit, slowly building the cadence, then spin out as hard as I can, for as long as I can, (which, without a HRM, I take to be the nearly feeling sick/giddy stage, rather than actually feeling sick/giddy stage), then I slow down for a bit in relative terms to let my pulse / breathing slow up a bit, then go as hard as I can again etc … (repeating until either I’m worn out, or bored (& worn out usually comes first)), finally warming down, getting off, doing some token stretching, having a shower, then having a cup of tea and some cake (which is the best bit).
20 minutes maximum end to end (excluding the shower/tea/cake bit), and that’s a struggle (mentally) – there’s no way I’d be able to grind the miles out on it at lower intensity. If I had any more time on hand than that, (but not too much more) I’ll go out running, which I also dislike, but at least I’m outside. If I’ve got more time, I’d try to ride.
I’m an old man now, and I’m not training for ‘anything’, so grabbing a quick 15-20 minutes of exercise every couple of evenings is all going to be useful – it’ll generally help with heart/lungs/bloodflow if nothing else. I can see the benefit in using a turbo for interval sessions / part of a structured training plan, even tho’ I just make it up as I go along.