Manufacturers sometimes use multiple grit numbers on their stat sheets. For example 500 - 2000 albaron. Does that mean 500 on 2 sides then 2000 on the next 2 ?

Most mfg.'s just list doing 4 sides (6 sides is usually just done when doing a true full resurface)

Here's a example using Storms surfacing guide recommendation:

To get a 4000-grit Factory Finish
1. 500-grit pad – Sand firmly for 30 seconds on all four sides.
2. 2000-grit pad – Sand lightly for 10 seconds on all four sides.
3. 4000-grit pad – Sand lightly for 5 seconds on all four sides.

And then there's speed of spinner at different grits .A lot of variables to take into account

Most mfg.'s just list doing 4 sides (6 sides is usually just done when doing a true full resurface)

Here's a example using Storms surfacing guide recommendation:

To get a 4000-grit Factory Finish
1. 500-grit pad – Sand firmly for 30 seconds on all four sides.
2. 2000-grit pad – Sand lightly for 10 seconds on all four sides.
3. 4000-grit pad – Sand lightly for 5 seconds on all four sides.

You've got to be VERY, VERY carefulwhen doing a full 4 sides.

When dong 6 sides, you have to be HYPER careful with pressure and, I STRONGLY suspect, you have to be super careful and use ONLY brand new pad, lots of water (or none at all, which is dangerous to your health) and minimal pressure to insure what you're using/getting is the precise grit level you want/need.

Unless I'm doing a full resurfacing, I use only 2 sides and then I am very careful with the kind of pad I use and the shape it is in. If you try to do 4 sides, I'd bet that 9 times out of 10, you use too much pressure and you wind up with something much,  much finer than you wanted or needed.

I suspect that you, in general, think you (in general) are being thorough, but what you (In general) wind up being is too much of everything.
(Not you personally, Aloarjr)

You've got to be VERY, VERY carefulwhen doing a full 4 sides.

When dong 6 sides, you have to be HYPER careful with pressure and, I STRONGLY suspect, you have to be super careful and use ONLY brand new pad, lots of water (or none at all, which is dangerous to your health) and minimal pressure to insure what you're using/getting is the precise grit level you want/need.

At the lower grits (360, 500, 1000) I feel more comfortable doing 6 sides. It might be overkill, but I like the thought of more completely hitting the ball.
 
So in the example of achieving Storm's 4000-grit finish, starting with the first 500-grit step, I'll do 6 sides at 20 twenty seconds instead of 4 sides at 30 seconds. Total time remains the same.
 
Above 1000, I back off to 4 sides. The grits aren't as aggressive, and there is less chance of creating problems. There isn't just one way of doing it, but I've had success with this method through the years.