It's a good question. My take is that the quote from one of the sibling comments -- where someone's dad talks about aging as 'boiling down to your own true essence' -- is actually wrong. I think there's a lot less 'true essence' and a lot more path dependency. In my example, is woodworking and European travel true essence? I suppose it's possible, but I don't think so. I think it could have just as easily been something completely different.
If all else were equal, it might be fine to pick something you like and just exploit the hell out of it till death. But I don't think all else is equal. Perspectives on the world, skills, knowledge, versatility, resilience -- an anti-caricature penalty on all this stuff seems good in a whole bunch of ways, even if I concede that you might be leaving some unexploited fun on the table.
Like I said, I am open to being argued out of this opinion; but that's where I am so far.
I think it depends on the person and there's no good answer. For some folks it will be sticking with what they know and trying to "exploit" it as deep as possible, while for others it will be "exploring" as wide as possible trying everything out, and for everyone else it'll be some mix of both.
To counter the anti-caricature penalty, there's also the stereotype of the older person that never found something to anchor them in life. This stereotype of an older person never found a hobby, friends, community, or partners and travels from place to place constantly searching and consuming. Most people are probably in the middle and most people relative to themselves probably become more focused with age.
I like this framing. The sweet spot would be finding a balance between having enough to cohere / give purpose / motivate, but not enough to capture all activity. So you'd want to monitor the situation and course-correct depending on what was happening.
And, like you said, some people would be happy being totally captured by woodworking / European travel, and wouldn't see it as a problem. And maybe some people would be happy in the anchorless, 100% drifting way, although I personally am suspicious of that -- if you have to choose, being a caricature is probably better than being completely un-anchored.
The stopping problem is a big part of it but I think also the older you get the less concerned you are about social conformity. You just do the things that make you happy regardless of what the young people think.
In the beginning, you explore. Later, you exploit by doing more of the things you found fruitful.