Yes, indexing something like 5 at a time would certainly help speed things up, though would increase the complexity of the software quite a bit. Would also be problematic with initial condition expectations to know where the machine is up at power on. Certainly an efficiency gain could be had.

I looked at the igus N series linear rails, which are definitely the cheapest. Unfortunately, there is just too much play in them. Accuracy would be sacrificed in a big way. The T series however is much much better, and the ones I have acquired for the job.

The X and Y are pretty easy, but creating the head with the Z and C is difficult. I've gone through 18 designs in CAD. I looked an belt driving system and a range of linear steppers and methods of implementing it. So far, I'm using igus T rails for the Z and servo motors to move it, as it has presented the most practical solution. The C is done with a tiny 1.8 degree bipolar stepper. The indexing by a separate servo motor actuating a pin, nice and fast. I'm only targeting one pickup head, indexing pin and a paste dispenser. For larger components, I can change the head, but will probably just have the machine paste the footprint and place it myself by hand... unless there are a lot of heavier components where changing the pickup nozzle is worth the trouble.

I kept getting stumped by being able to actually make it, so I diverted to putting together a small CNC first which will be used to machine the parts for the pick and place.