Worth signing up for a maintenance plan or just pay as you go?

[zephyrwright]

My 2015 528i just crossed 130k km and I'm debating whether to keep it for another few years or start looking at something newer. If I'm keeping it, I'd rather stop dealing with surprise bills every time I take it in, so I've been looking into an affordable scheduled maintenance plan for BMW cars to spread the cost out instead of getting hit with a big number every few months. But I've heard mixed things. Some people swear the plans are great because you know exactly what you're paying and the shop keeps a proper history of everything, others say they ended up paying for services the car didn't actually need. I'm not chasing the cheapest price, I just want predictable costs and someone who genuinely knows these engines. Has anyone here signed up for something like this in the UAE? Did it actually save you money over paying per visit, or did it just feel that way at the time?