The jump from Research III to Research IV is too huge, thanks to the Robotic Assembler
In order to jump from Research III to IV, you need Lab Equipment IV, which requires Electronics II, which requires producing PCBs and poly silicon. That's fine. Similarly, you need Construction Parts IV, which requires Electronics II as well.
But to make Construction Parts IV, you need a Robotic Assembler. This needs Maintenance II - also fine. However, the Robotic Assembler needs Computing, which needs a Datacentre, which immediately forces you to upgrade to Maintenance III! And that needs Electronics III, which means that the polysilicon line you've just built is obsolete and needs upgraded to produce mono silicon, plus you have to spin up gold mining and refining and microchip manufacturing.
This is a ridiculously huge step. If you could make Construction Parts IV in an Assembly (Electric) II, then this would be the right size of step - and given you can make Construction Parts III in an Assembly (Electric) it doesn't make sense to skip straight to Robotic for Constr Parts IV.