Some recent conversation on the topic. I quoted a relevant blurb but go from the top it’s a good thread:
You can blast out to maybe 10 for a while but most of the time this is going to include side experience from follow-on activities like crafting batches finishing.
Bashing the gleamball is practically the least of the XP you can get from a big stack of gleam. This is less true of mining, and both are more profitable than placing blocks but if it’s all about the cubits maybe a couple hundred hours with a stack or two of lucents will do you.
Just smashing out 3000 levels is a lot though. 