How to focus on all 3 disciplines?

What are people’s experiences of throwing in high focus periods on one particular discipline? E.g. a week doing predominantly swimming - or a month, etc.

I am contemplating my winter training towards the end of a slightly disappointing season due to injuries, bad luck and work and social commitments. Swimming is my weakest discipline and to make a breakthrough I really need to throw in some big swim weeks (5+ sessions). Cycling is my strongest discipline but I neglected it a bit much this year and want to get back to form - plus I built up a Lucero frame yesterday, it’s looking very stealthy and I’m going to get a lot of stick if I can’t do it justice… Running is strong when all is going well but I’ve had a tendency to run too long/intense and infrequently which has contributed to injuries so looking to build and maintain a running base by running more frequently with some shorter and lower intensity runs in there.

So I’m trying to figure out how to achieve the necessary improvement in all 3 legs, given that my already precious time is being further stretched by having to do a lot of core/flexibility/balance work to prevent injury recurrence. I don’t think my normal approach of aiming for 3 sessions per week in each discipline will yield the necessary improvements in swimming. But I also can’t neglect the bike/run too much, even in the base period. Am thinking:

November-March - alternate ‘swim fortnights’ with ‘bike fortnights’. Every week would feature at least 2-3 runs, but during the swim fortnights I would aim to swim 5+ times a week and probably a single ride each week to maintain cycling. The bike fortnights would still feature at least 2 swims a week to maintain technique, but also at least 3-4 rides a week to build my cycling base back up. Every 4th week would be my recovery/testing week - would coincide these with swim fortnights and would limit them to 2 runs and 1 ride, but would still feature a fairly large load of swim training.

Does this make any sense from a physiological point of view or people’s own experiences?

Rick Niles wrote a book that deals with this exact thing, precisely this.

his website is www.ranfit.com

Most folks recommend 3 - 4 weeks of an emphasis.