I'm doing my first run, and focussing on designing everything myself without looking online. I'm producing the first two types of card, and have a belt to move the cube. I have (presumably like many others) discovered I need a circuit to count resources into and out of the cube machines. As I'm using pulse counting, it's important that combinators don't brownout. That looks like exactly what the backup power turbine is for, nice mechanic.

My initial design used several conditions (enough raw material in the machine, output empty, sufficient steam in storage), and I had an indicator lamp for each one. Turns out the turbine can power 20 combinators but only four lamps. No problem, placed a second turbine - but that didn't actually fix it. Which feels weird. I think this bug is related: https://forums.factorio.com/viewtopic.php?f=48&t=79566 . I think you could get the same behaviour with combinators only, though you'd need some half-in half-out of the coverage area to get more than 20 connected.

Suggestion 1: adjust lamp power from 5kW to 1kW.
Suggestion 2: Just using combinators and (1kW) lamps, I think the maximum you could fit in the turbine's coverage is 32kW. If it doesn't upset balance anywhere, I would be inclined to up the turbine to 32kW, so you can cram combinators and lamps in to your heart's content.

I realize this isn't at all what this thread is about, but to make it easier for you to not have to make circuits to count input in to a machine, you can use the Inventory Sensor mod if you want.

It's unfortunate to have to work around an engine bug, but I'm tempted to follow your suggestion. Maybe 2kw for lamps would be enough of a change? How many do you have per turbine?

I had one lamp per input or output (whether fluid or object), plus one for steam level if the recipe uses power. All lamps on = ready for cube = inserter enabled. Any lamps off -> hover over lamp -> click attached combinator to see why. I had two cube consumer control circuits per backup turbine. So up to about 10 lamps. My solution was to put the lamps outside the turbine range - which works fine. It's just that the process of coming to that arrangement was frustrating rather than fun because it's not obvious why adding more turbines doesn't work, so a "tips" page would be an alternative workaround.