I'm not sure what I'm trying to write. There's probably no point to this post. Maybe it's advice to myself.
Let's start with traveler's luck: it's that glorious moment when either you've not planned properly or your plans just didn't work out, and yet something happens that magically makes everything alright again. The best example I've got of this is on my very first cycling trip in Japan: we finished our cycling day quite late, couldn't find a camp site and then decided to go to a hilltop onsen instead since we were there anyway. The place also happened to have a restaurant so we had dinner there too. After dinner it was already pitch black outside, and we asked the owner if he knew any place nearby where we could camp. And the owner just let us stay right there, next to his restaurant/hotel, to put up a tent right there. The next morning we woke up with the most beautiful view of the tiny islands scattered around the area.
Another great example was when I reached the southernmost point of Kyushu. There happened to be a free-of-charge camp site right there next to a lovely bay. Due to pure serendipity I happened to arrive there just as two other traveler's arrived too: one by car, one on foot. We hit it off great and traveled around together for the next few days.
It's not always good, of course. In my case I often/sometimes run into trouble when not pre-booking a place to stay. I'd say for those times that you can't magically find a nearby hotel or camp site, it's 50/50: either you end up staying in a bad location (overpriced hotel or unsafe/noisy/dangerous tenting) or you end up being rescued by a local who either shows you the perfect spot him/herself or points you in the right direction.
It takes the right mindset to forget the bad days and remember the good ones, and to push your luck more in the future. It depends on your personality too, and might be difficult to change. You have to be somewhat in your comfort zone to give luck a chance. If not in your comfort zone, then at least you should have made some hypotheses about how far out of your comfort zone you are going to be if everything turns to shit, and if you're going to be ok with that.
In my case, my comfort zone has two edges: safety/security (which is a non-issue in Japan not even worth discussing), and cold. I've had some really cold nights in a tent in the past, mostly due to a crappy sleeping bag, and I've also been freezing cold from cycling in cold weather and working up too much of a sweat. It's nice to be (somewhat) prepared for the cold, but in Hokkaido the worst-case scenario is that you can't find a camp site or hotel and will have to sleep somewhere in the middle of nowhere, out in the open. Then you'd better hope it doesn't rain..
Modern technology enables you to eliminate luck from the equation entirely. Thanks to portable internet devices you can have internet all over the country you're traveling in. You can pre-book hotels on the fly, you can map search anything you want. There's no need to ask locals, no need to leave things to the last minute, everything can go as smooth as you want it to go. My advice: don't do it. Don't rely on technology. If possible, don't even bring the internet with you if you can avoid it. If you have it then the temptation to use it is just too easy.
I myself am a terrible example of this; during my current trip I've only done unplanned camping once, and it was a disaster. Every other time I pre-searched camp site locations before setting off, knowing how far they'd be. Most of the time on the days that I didn't have a hotel pre-booked or an endpoint for the day decided, I ended up in hotels rather than camping. It's difficult to take a chance when you have a certain positive (or at least neutral) outcome available to you. You can't swing the traveler's luck roulette wheel if you're staying in business hotels every night. Try a camp site or a youth hostel. Talk to people. Go on adventures.
Perhaps I'm being too careful. Perhaps I'm just acting my age according to my already un-adventurous personality. Perhaps after I've reached Wakkanai I'll feel re-entitled to a new adventure. All in all, this post is an assessment of a trip that is not yet finished. The moments that will be remembered and the moments that will be forgotten are not all accounted for yet.