Training for multiple goals at one time poses significant challenges and you are wise to consider how you can balance the competing demands of these to rather distinct goals. By competing demands I mean the following:
1) Being strong on a high altitude mountaineering expedition is going to be almost exclusively reliant upon basic aerobic fitness. The ability to hike steeply and slowly uphill with a pack for hours on end. Pretty basic and easy to comprehend.
2) Being strong on short hard technical climb demands an entirely different set of physiological qualities, whichI am not going to detail here.
I don’t know your training or climbing history and maybe you waltzed to the top of the 20k climb you did and set a speed record while doing it. If so then the following comments should be disregarded. If not then pay attention.
Training to enhance #1 above, especially in light of the fact that this is new altitude for you and you do not have much time before you leave, will or at least should, consume a bunch of hours of low to moderate intensity running of hiking up hill. The best stimulus for aerobic adaptations is the duration the training. Volume is king here. More is better.
Can you manage to up your aerobic training volume significantly while still going ice and rock climbing 2 days a week? Again I don’t know what you’ve been doing and maybe you are already capable of going car to car on the Grand Teton in 6 hours. If so disregard pretty much everything I am saying here. This is why there is no blanket prescription that fits all cases.
It comes down to these 2 factors:
1) How fit are you currently and how much do you need to move the aerobic needle in these 18 weeks? How much can you handle work wise? Only you can answer.
2) How important is this 24k mountain goal? If it is very important, what are you willing to sacrifice to achieve it? I mean the ice and rock you are talking about will be there but will you get another shot at this peak?
I can tell you that when Steve was training hard for his big goals, his climbing buddies stopped calling him to go climbing. He’d typically answer: “Sorry but I have to train”. This long term view paid off for him. Most climbers are not willing to sacrifice the short term gratification for longer term goals. There is nothing wrong with short term approach if its what you want. But it’s probably almost impossible to have your cake and eat it too.
The 24 week plan follow exactly the periodization program laid out in our book. The shorter plans all involve some compromises due to their reduced lengths.