I came to realtime vfx from a career in film/commercial work where I was almost exclusively specialized in simulation and rendering. It does take a long time to get the feel of settings and cut down on iterations for sure, but I agree that the years of experience add up and you do get faster. For me, Houdini has been a life saver. I always start my sims from a previous project where my settings are already pretty dialed and modify from there. I also reworked the texture sheets tool that comes with SideFX Labs (Previously game development toolset) to use Arnold instead of mantra which started saving me hundreds of hours in render time. I haven’t checked out the new render engine Karma but that may replace my hacky Arnold solution. With my current setup I can get some quality fire, smoke, or explosions in 2-5 days depending on the project and client feedback. I work for an outsourcing company so we have to be pretty agile and we work within every budget, quality, style and platform restriction imaginable.
I will say, I started the vfx department at my company and training my artists in simulation and rendering is always the final stage. It’s such a deep field and as we’ve been talking about it takes time to start seeing satisfying results. So I get everybody solid on shader math, laying out uv’s for vfx animation, making textures, and all those aspects of realtime vfx before I ever plunge them into simulation. When I do I give them all my pipeline tools and my guidance and it still takes a good month before they’re making anything quality on their own. A big hangup a lot of my guys have in the beginning is keeping the resolution of your sim as low as is useful instead of waiting for a full res sim when you’re still making big decisions.
I second what @HowardM says, just keep absorbing tutorials and stick with it. For real the last 8 years of my life have been dedicated to simulation and I’m still finding ways to get better and faster. I did my first fluid sim on a garbage laptop in college. It took 2 weeks to sim, 2 weeks to render, and it still looked bad haha.