Back in the day, I spent a couple of years as gamesmaster for what would now be called an RPG that I basically made up myself, based around the background I was using in my Lyra series. Paper-and-pencil gaming was fairly popular then, at least in my social circles, so there were quite a few other games, gamers, and gamesmasters running around.
One evening, a bunch of us were at a party and one of the other gamers was complaining bitterly about how cheap his gamesmaster was – his group would get almost killed fighting a dragon and then discover that its hoard consisted of a rusty dagger, six copper pieces, and a couple of tiny, badly flawed gems, for instance. He wanted to know why they never got any good spells or powerful weapons. Without even thinking about it, I shot back, “Because there is no spell or tool, no matter how cheesy or apparently useless, that the gamers cannot find some way of using to short-circuit the gamesmaster’s most carefully worked-out plans. The only hope we have of keeping you guys under control is to limit your obvious firepower, so that you have to work a little harder for it.”
I learned a lot from being a gamesmaster, but that was possibly the most useful thing of all. It applies to writing in two ways: first, if your heroes get too powerful too fast, they’ll overcome all their problems too easily. So you have to jack up the level of problem they’re dealing with and the power level of the bad guys, and next thing you know, they’ve gone from needing to save the village to needing to save the universe, completely bypassing saving the kingdom, world, planetary system, and galaxy along the way (which can be really inconvenient if you end up writing a series, because you could have gotten several more books out of saving all those other things along the way).
Second, anything a writer puts in a story has implications, and if you don’t think about them at least a little bit, you can run yourself into believability problems. I recall one story in which, early in the story, it was established that a) in this particular future, people had figured out how to manipulate gravity, and b) they’d used this technology both to make their space stations comfortable and to make really deadly hand weapons.
So far, so good. But then in mid-book came the scene in which Our Heroes were waiting for the fork lifts to unload their cargo, and I set the book down and didn’t pick it up again for a long time. Because from the description, these were obviously normal 20th-century mechanical fork lifts, and if this society had whizzy gravity-control based hand weapons, there didn’t seem to be any reason why they wouldn’t have applied that technology to unloading space ships.
This author was not a beginner, nor was he terrible or careless. He was, I suspect, simply so wrapped up in his story that he didn’t think through the implications of having gravity control. It happens to a lot of SF/F writers, because the things we come up with haven’t been reality-tested. In real life, when someone comes up with a nifty new technology or gadget, there are billions of people to look at it and think “Hmm…how can I use this to make my life easier?” And it’s fairly obvious from real-life experience that even the people who invent various new gadgets cannot always predict how people are going to use those gadgets in real life.
When I come up with a nifty cutting spell for my characters to use against the bad guys, there’s nobody but me around to say “Hmm…how would that help me dissect animals in the lab?” or “Hey – that’ll make butchering cows much easier!” or “What a great thing to use to cut the grass! I wonder if I can use it on trees, too?” If I don’t think about the implications, nobody will. And when I’m focusing on getting my characters out of a sword fight and on to their next adventure, I’m not really thinking about cutting the grass or doing dissections or the hundreds of other places where a cutting spell might be useful in everyday life. I have to stop and think about the possibilities for a while (and even then, I probably won’t come up with all, or even most, of the obvious ones).
And there isn’t time to think about all the implications of each and every thing one puts into a book. When you’re inventing a whole imaginary world, there’s simply too much of it to get everything. This is one of the reasons I prefer to do a large chunk of my worldbuilding in advance – because as long as I’m not head down in finishing the fight scene, I can take time to consider the implications of at least some of the things I’m putting into my imaginary world. I can, with luck, spot the things that could throw things out of balance, and put some limitations on them. I can talk about them with friends who will spot different problems from the ones I see, simply because they have different jobs, different life experience, a different point of view.
I’m never going to catch everything. Even the best writers occasionally miss things. And there are a lot more of my readers than there is of me; it is inevitable that some of them are going to spot places where some technology, spell, or ability that I’ve put into a book has important implications that I haven’t thought of. All I can really do is stop and think…and try and make those people have to work a little harder.