Very well put. My first ever DIY mix was supposed to be the perfect clone of some factory juice i had used a lot. I had analyzed it in my head for days, bought a bunch of appropriate flavours, determined what percentages i would need, and made 500ml at once, because i couldn't go wrong right? Classic n00b mistake, worst juice i had ever tasted.I know just what you mean. I've settled into a routine of making just what I need and not doing much experimenting. I have my 10 or so ADV's and rotate them so I find myself mixing maybe once a month and only mixing those flavors I get low on. My perfection days are pretty much over and I've adapted a close is close enough attitude.
I then figured it just wasn't accurate enough so started weighing, testing micro amounts. Didn't help either.
Moved on to getting better flavours, wrote down every mix until several obvious patterns surfaced.
Nowadays i have an average 10 to 20 steeped singleflavour juices and make daily mixes on the go. Never the same, always varying ratios, sometimes without that one flavour because i need to restock it. I don't even bother anymore to use an exact percentage per flavour: i just take a 10ml flavour bottle and add it to an average 300ml of base, or less, or more if there's just a bit of base left.
Also my vapebrewing has reduced to maybe 4 to 6 times per year. I literally need to dust off my brewlab every time i pull it out of the closet.
Still do follow this topic though, and find new tips all the time.