Will a 1K to 5K spread suffice or would adding a 2K stone better fill the gap?
Well let me say this about that :
If you enjoy big O' mirror polished bevels on your blades then to get them you need to work your way through several grits.
If you just want blade edges that are super sharp and are willing to look at roughly ground bevels then no you don't need many grits. You can even power grind the main bevel to get the dull and dings off the edge and then take that edge to the finest stone and put a "micro bevel" right on the very edge at a couple of degrees steeper and viola you have your sharp edge.
I think that is sharpening blasphemy and . . . just too easy

. I like the wide mirror polished bevels. It's not the easy way but it's the cowboy way.

I go Shapton Pro 1000, 2000, 5000, 8000 (some times up to 15,000)
I've got a Norton 4000 I can sneak in there if I am getting too crazy.
This is all for looks you understand
The micro bevel has so little surface area it is possible to sharpen away the coarse scratches fairly fast with the finest stone. For larger bevels it would take hours to do that so the other stones are required.
Pardon me for using my woodworking tool photos but I already have them and they are easier to see than my pocket knife photos.
OOPS ! I'm answering an old thread. Oh well maybe it will help someone else. Or at least help make the Shapton guys rich beyond their wildest dreams. Ha, ha, ha.