Regarding the time spent constructing the world, we all have to work with the number of hours we have. Those hours have to be spent as we're able, exercising all the usual principles of business: 1) increase expenditure by increasing the number of hours and 2) decrease overhead by requiring less money to be spent on things that don't matter or fail to be profitable.
That's all it is, really. I have a daughter that's 27 and doesn't need to be taken to soccer games or schlepped to relatives. I have a partner who enjoys her free time; every day we spend two or three hours in personal time, enough for both of us - sometimes more if we find the opportunity. I've lost all interest in burning off 8-10 hours in evenings at a bar or a restaurant; I don't spend six hours the next day recovering. I live in an apartment. I don't build things or watch sports (or any television, for the most part) and household chores are the minimal sort for a chair-bound geek. I try to get myself out every day for physical effort but that can usually be done in tandem with some chore or community time. Work eats about 15-30 hours (as I struggle to maintain even this many hours in this bad economy). These adjustments to my lifestyle leave me with around 50-65 hours a week for research, reading, writing, working on my world and managing other smaller projects, something most people would find deathly dull.
I can afford to spend time with research and development, updating rules and my wiki, putting unnecessary time towards aesthetic features and plugging away at this blog. Most of my readers can't. They'd find my daily grind boring beyond all reason and they owe huge amounts of their time to work, spouse, children, social commitments, activities well out of the RPG culture and a nest of other busyness and priorities.
Okay, so you have two hours a week to work on your world; nothing wrong with that. You can squeeze about twenty minutes between coming home from work and sitting down to dinner most days, you can sometimes work for as much as an hour while others are out to get their haircuts and when you're lucky you can manage all of 90 minutes on a quiet Sunday morning when you're up and everyone else is still asleep.
Use that time well. Don't spend it as I spend it, don't rebuild the combat system or spend the time making a new set of monsters. Don't blog! For blazes sake, you have two hours to get the game ready come Saturday and you're going to need all 120 minutes to draw out a half-decent town setting where the party can scuffle with a bunch of guards or the LBCR (Local Beggars' Combat Regiment) under the command of a lowly thieves' guild member. Those are the things that matter!
Sure, you can look with longing at tables you'd like to be rewriting or that skilz system you've long considered hacking and building into something to change the player's game, but you haven't got the time. You have to meet the boys and get out to see who wins that important game between the Packers and the Broncos or between Shrewsbury and Macclesfield. You can't write that new RPG, you and the person you love wanted to live in a house so there are vegetables to harvest and lawns to mow and trees to prune. Forget making that megadungeon, Jeremy's garage needs painting and you said you'd help this weekend because six weeks ago he helped you rebuild the kid's playhouse. You don't have time to write a 72-part series on the Rolemaster rules, you've got to work every Saturday and Sunday until Christmas because your boss has you combing numbers for the quarterly report that's being published in January.
Please don't take that as my saying your life isn't up to snuff. I'm not saying that. I am saying you chose that life. You're always going to have more money than I have and you're always going to have a place to live. Your boss is going to treat you with respect and you'll probably spend this year's vacation in Amsterdam or Sydney or viewing the ruins at Luxor. YOU have a great life. You made up your mind to have it and let's be honest, you love that apple tree in your backyard that takes two days to prune because it stands 23 feet high. You love your life.
But it means you've got to prioritize if you want that life and the experience of being a DM - because being a DM soaks up as much time as catching all the basketball games in a season or having a big yard that needs work every summer or surrendering your free time to work sixty hours a week so that you'll make project leader before 30. There's no half-way that doesn't compromise your "vision" of a wonderful great world that you imagine yourself someday running - just as there's no halfway with your family or that career; you wouldn't compromise either of those, would you?
I'm only saying that you can either figure out a means to find the time necessary to really design your plans, then stick to that schedule, or accept that, with many things, elements of your world have to be straight out of the rule book. I know that doesn't sound like me, I'm always advocating the do-it-yourself campaign - but that's because I'm talking to people who, like me, have more than twenty hours a week to give. If you haven't got that, learn to appreciate the campaign rules designed by others without quibbling. Save yourself the time. Be realistic.