The big issue with Cetus is there is no manual leveling of the print surface. A thick raft is used to build a level surface before starting the intended print.
This takes considerable time and some wasted material. The material consumption is no big issue unless one is close to the end of the spool.
PETG is particularly sensitive to everything being “right” with initial layers.
I use G-code produced with Simplify3D. It has much better control of variables than offered with the stock UPStudio slicer/print software. There is a new Beta for UPStudio which shows promise but stopped working on my WIN10 PC.
UPStudio is still required - to load 3rd party G-code to Cetus. Simplify3D cannot communicate directly with Cetus.
PETG extrusion temperature is 150C. with a 90C bed. I am presently using 0.25 layer height with +200% for the first layer (0.50 height) This is required to help compensate for the un-level bed. I am using 100% extrusion flow with a 0.4 diameter nozzle. non-solid infill is set at 150%
These figures don’t seem extreme, and what I have found as necessary to get good non-raft PETG prints on Cetus.
Sone factors when set too high tend to push the Cetus extruder close to its flow limits. Missed steps (clunking) can be heard if pushed harder. This is the feeder gear slipping on the filament and cutting a notch. This will usually stop filament feed.
Travel (print) speed is also quite low with PETG, 2100 mm/m with under-speeds of 60%. Rather slow but PETG is also speed fussy.
Note Well: These are setting that work for me. Your results will certainly vary. Use these settings as an example of where you may have to go to get satisfactory PETG prints on a heated bed Cetus.