Last week we spent some vacation time at the beach in San Diego; it's a trip my family takes most summers. Normally we stay within walking distance to the beach. This year, however, we planned a little late and ended up in a hotel about a mile away from the ocean. No problem, I thought - we'll just load the car up with all our gear in the morning, get a good parking spot, and set up camp on the beach for the day. Plus we're saving about $50-$75 per night (I rationalized.)
Except, in the process of loading a bunch of gear (and tired people) at the end of the day, I left 2 wetsuits laying on the rocks next to the car. $60 in rental wetsuits later, and with $400 in replacements waiting for me on Christmas lists, my failure to attend to details looks expensive.
Some things only need to be "good enough", like when I'm mowing/cleaning the yard on a summer day, knowing full well we'll have another monsoon in the next day or two to mess everything up again. At that point, I'm not looking for perfection - I just want the yard to look well-maintained... Good enough.
However, when success is really important, or when the task requires great effort, the details make the difference.
When you're trying to lose weight, it doesn't help to pay attention to your main meals if you spend the afternoon snacking on handfuls of this and that. The few hundred extra calories you're eating could easily be the difference between gaining weight and losing weight, even though you've put so much effort into shopping and preparing good meals.
When you're trying to save money or live within a tight budget, the few dollars spent here and there without being tracked - a coffee here or a beer there - could be the difference between ending the month in the red or in the black.
Of course the big picture matters too. But once you get the big picture right, you're not going to be successful without paying attention to the little things - the details make the difference.