I think the main advantage of planking is that it does not strain your back the way crunches do, which is why many have moved away from crunches, even the military. Doing a high amount of crunches at max speed is definitely not good for your back. We managed 2min of planks now, with shaking but no major discomfort. Could probbly reach 5min with some training soon. It's not spectacular, the world record is something like nine hours! We'll continue to do both with moderation.

Our little health freak event set back gym ambitions a bit but despite host unfairly labeling me as nagger, I found a gym very close to us that seems neat, will check it out next week and probably start membership with October. There's plenty of body weight training we can still do at home until then.