I have 2000hrs on one X1C printer and 1000 on another.
I tried Ludicrous mode the other day for the first time. Print time went from 32hrs down to 18 and the print came out just fine.
Why isn’t the printer just printing in this mode all the time? What’s the disadvantage? Is it hard on the printer itself? Do prints get f’d up more often? What’s the downside to this mode?
This was with some cheap crappy PLA+ filament that was 2+yrs old too and I didn’t even put it in the dryer.
It depends on what you print as to the outcome.
Your parts have decent contact to the build plate, are not too large and are solid parts.
The more delicate print with less surface contact will be shaken off the printer or inadvertently be knock by the head.
I haven’t tried it yet, but I love how they named it. 
Better to speed it up in your slicer.
I think the modes do not care about volumetric flow rate so if you are already at max vfr and bump up the speed you could push unmelted material through the nozzle, …
I tested the speed difference, and it isn’t a lot. However it you print a part that needs an interference fit, or to close tolerance it is inaccurate.
You can see the slight rounding of edges where the nozzle slows down.
For non engineering/structural parts it is fine, but default settings for anything you want to fit inside or outside something else!
“I’m surrounded by […]”
I believe Tesla first used the word “ludicrous.” It is yet another instance of a humorous usage being copied.
Actually, I think it was coined in the movie Spaceballs. (Hilarious btw)
It was.
The line, “I’m surrounded by …” was talking about Elon Musk.
