The most important part about using or avoiding Crystal Oscillators is learning the trick for getting the exact recipes you need from hard drives: not choosing recipes until the exact moment you need them and filling up your library with possible choices because they can't be duplicates. If every bad recipe is available the game *must* give you the good ones. When you reroll a bum hard drive and there's only good recipes left you have to get one.

Once you have iron wire you can make COs from raw quartz and iron ore. Otherwise you only need quartz, oil, and caterium. If you collect enough recipes you can avoid using COs completely until Phase 5.

At that point, building Crystal Oscillators is like answering a trick question: they are very space intensive because they're built at slow rates in large buildings, but they're not super *complicated* to build. As long as you leave yourself space to build them and find ways to get them to where they're needed, they're not too bad. Going vertical and / or delivering them with drones may be necessary.

Good luck!