Step on-time step space

So I have a question to get me edumacated   
So, I've seen a pile of questions related to Step on-time and Step space and it seems there's just a general rule of thumb for some numbers to put in as starting points. unfortunately, it drives my mind crazy. I would gander to think that every driver has a specific number for it but from looking at tech documents it is a bit hard to decipher especially when I don't really understand what it relates to (well somewhat understand). so, if I were to look at say documentation for the Gecko 201 because PNCconf has those settings already defined how would I pull that info out from the documentation or are those settings readily available because it's a drive that has been used more prominently?
I ask because I recently emailed the tech / support department at Stepper-Online and they had no idea what step on-time and step space were. found it rather odd that they would not know what info it was I was after. Their documentation doesn't seem to be lacking and appears to be about as detailed as say Gecko documentation.

So is there no way to pull info from the tech docs to get this information?
How would one know exactly how fine-tuned you can take a driver. I run the DM542T from stepper online my settings are
Step On-time 5000
Step Space 5000
Dir Hold 10000
Direction Setup 5000
These settings do seem to be fine for my setup as I don't believe I've had issues, but I've only run this new setup a few times for testing.
But if you look at the Gecko 201 it has settings of
Step On-time 500
Step Space 4000
Dir Hold 20000
Dir Setup 1000
Kind of a big difference and granted it might not be a fair comparison. But some of those settings go in different directions from what a base line setup would be. how would one come to the conclusion that I need to subtract 4500 from step on-time and bump Dir hold up another 10000.
Like I said my table seems to be running with no issues in traveling so I really don't need to make adjustments. I'm just curious.

 
I'm guessing this is the info we are referencing or am I way off on that?
 

Yes

So how do you take that info and translate it into Step On-time, step space dir hold and dir setup?

Step time = T3
Step space = T4
Dir setup = T2
Dir hold (missing from chart)

One really important thing to understand is that these are all _MINIMUM_
timings so unless you run into speed limitations, there is no reason to use
minimum values. In fact using minimum values increases the chance of problems

Awesome that is what I was trying to understand. from what I've read, having these numbers off can lead to missed steps or no movement. Are there any other issues that would lead one to believe they have these numbers off?

Also, and of course in being curious PNCconf lists the gecko 201 with minimum values listed, in the dropdown choice, if I read the Gecko 201 doc correctly.

Most common issue is too short step time, this can led to erratic
behaviour or no motion at all.

Too short direction setup or hold can result in lost or gained steps at reversals
but since reversals only happen at near 0 velocity (and consequent long times
between steps), there is little cost associated with setting quite long direction
setup and hold times (that is 20000 ns is probably OK for anything...)

"having these numbers off can lead to missed steps or no movement."

No, having these numbers too low can lead to missed steps or no movement.