Inline assembly machinery is very useful for assemblies of four or more components.  They provide more design flexibility and much better operator access than what is practical on a rotary dial system.  Systems are available in an "over-under" chassis or "carousel" chassis.  Typical speeds for these systems range from 10-30 cycles per minute with pneumatic pick and places to 50 cycles per minute or higher with mechanical, cam driven pick and places. 
Higher throughputs are achieved by tooling multiple parts and making
multiple assemblies per cycle.