To minimize retractions and travel when printing several objects, some slicers produce gcode for sequential deposition when each object is built in a traditional manner bottom up layer by layer before starting a new object. Of course, there are limitations caused by the hotend geometry :
So bulky hotends don't allow for this trick to be used wen sequential pieces are closer than several centimeters. If there where hotends with minimal end effector geometry (needle like, much like drill bit on CNC) we might even do things like spiralizing contours of a single object. This has also potential for other tricks like producing interlacing layers for better layer bonding etc. I wasn't able to find any ongoing work on minimal geometry hotends. Any links? And what might be the challenges in making one? heatblocks and heating cartridges are out of the question but nichrome wire and a fast PID heat controller might do the job.