Here's an idea I'm trying out with a deck I'm trying to build. It may be a bad idea, but we learn through failures.
I'm building a a Runner deck with the idea that I have only 15 or 16 slots to put cards in (45 card minimum ID). In other words, I'm taking 3 copies of nearly every card in my deck. The idea is to force me to focus on the central idea and purpose of the deck -- to set the foundation -- as I start testing it. The goal of early testing is not to win games -- although that is always a bonus -- but to see if that central idea is something that I can actually get up an running.
I've already experienced the obvious limitations of this approach in games: Dead cards, lack of answers to certain Corp cards or strategies, predictable lines of play. But even that is really helpful information because it helps me spot where I need to slot in some 1x and 2x cards down the line and where I can adapt my play.
Another bonus for me -- at least -- is the clarity of such a simple deck. One problem I get when I net deck is that lots of highly polished net decks have lots of little moving parts and cards slotted in for special purposes that are not immediately obvious to a player who did not build the deck. So, when I get my hands on that deck, I can have a hard time figuring out how all the shiny parts and pieces are supposed to work together or when they should be ignored.
I'm a long way from a viable tournament deck in my current build, but I kind of like the process at the moment. If only I could find more time to play and test. I certainly get why people say they don't have time to develop their own decks.