I have learned over the years what works well for me, and I have learned over the years that what works well for other people and they are not necessarily the same. The idea that you first set a goal of early retirement, then decide on a strategy to reach your goal, then devise the tactics to implement that strategy is logical and compelling, but it never worked for me. I had a vague idea that I wanted to retire early, I knew that would involve saving and investing in some way, so I worked out what I thought I could reasonably save from each paycheck. I measured how much I was saving, I monitored how much I was spending and how happy or unhappy I was with that level of spending. I spent more if I was too unhappy. I challenged myself to save more if was happy enough. Every once it a while I look at my pile and try to see if it will help me reach my goal.
Eventually my savings piled up and I needed to learn how to invest them. I made a few mistakes, read some books, made a few more mistakes, tried a few more ideas, some better than others, and finally settled on a mostly passive approach that I can ignore for long periods of time and still do well with. Once it a while I check to see if it looks like it is heading towards that goal.
This is kind of bottom up instead of top down, and I acknowledge it focuses first on tactics and not on goals. When I try to do it the other way around I quickly get frustrated and want to give up on the whole idea. So I go with what works for me. Once in a while I invent a metric like %saving of gross or %savings of net and see how I'm doing. Mostly comparing against my previous self, since it is hard to find these kinds of numbers for others. Maybe look at networth by age a little. It's hard to compare much of this. What about people with pensions (much higher than what I spend in a year), they make me so jealous. That's not helpful, so I go back to managing the tactics, since that's mostly what I can control.
Probably this means that I am missing some bigger picture idea, such as am I really maximizing my economic productivity in my chosen career, or should I be trying to get into something else. Too complicated.
On the other hand, this has also meant that when a catastrophe struck, like very bad investment losses, bad layoff or horrible divorce, my plan easily absorbed the changes and kept moving forward. I think if I was more focused on being at 95% of my goal and suddenly I was at 40% it would have been much more devastating, at least morale wise, and would have made it harder to keep trying.
LBYM to me means comfortably living, somewhere below my means. I want to manage wisely to make the most of the means I do have, but I still want to live comfortably. Finding the right balance between what I want and all the things I could have is something everyone probably has to find for themselves. I do not think LBYM means living as far below your means as possible, nor that it should be competitive (unless you want it to be, I guess, I don't want to do that myself). I want to be comfortable now and retire early and comfortably then. I'm okay if it takes me a little longer than it might have, if I get to be comfortable enough along the way. All the metrics that work for me to manage this are mostly based on tactics, not so much on goals, except for total portfolio size in relation to expenses wanted from it.
