hmm, 36 or 40 grit on a belt sander (the one tool that can handle nasty stuff like this). I did a wood piece like that using 60 grit 'mesh' sand paper connected to a orbital connected to a strong vacuum, but I went through a fair bit. If I went with a belt sander it would have gone quick.
The mesh abrasives (diablo mesh or abranet) last ALOT longer then solid papers with holes. But you do have to take em off the velcro and blow it out and wash them, but it cuts down materials cost. The way they work
1) for 15$ you get between 10-20 pieces of abrasive mesh and a special velcro pad with holes in it that has looser velcro then your sander.You align the velcro backer it comes with with the holes in your orbital sander, then you center them mesh on top of that, and frequently take off the mesh and blow it out with compressor and eventually wash it with soap and a nylon brush until it wears out then repeat.
The belt sander is the one tool that can handle mill-scale also on steel. Orbitals get clogged very quickly. Belt sander can surprisingly last a long time with the crappiest materials.
I would recommend a belt sander with the coarsest mesh you can get (typically 36 grit in the hardware store), then move onto an orbital with the mesh abrasives.
If you use a remover (not sure if you WANT to because it is a food surface), it might cut down on your abrasive use. Some people might suggest sending it out to get planed on a big planer for $50-100 or so.
The orbital sander SHOULD be less aggressive then usual if you use the mesh abrasives, but last longer because of less clogging.
I did a table top that was not respected and used a big butchers block for a long time. It was a very bad job. It is also made like your block out of glued wood bits. You will not find this job pleasant. I typically use the mesh abrasives (I stock piled them between 50 to 1000 grit for more money then most people want to spend on abrasives). I think its worth it, so long you clean em, and know when to use a fresh piece for a certain job instead of trying to get every penny out of it (so it increases your storage requirement because you need to segregate them after wear becomes unacceptable for certain jobs).
I get so sick of aligning the normal ones with holes that I just pay to not deal with that.
https://www.diablotools.com/products/DND050060H10IThe 10x life is a bit of a stretch, but I notice it the most on finer grits, with normal sand paper disks at 800 grit.. the life time is really really low.. the mesh really helps there IMO. Life time will depend on how hard the material you are using is, I.e. corian plastic will wear it out quickly (its filled with abrasives itself).
I will say though, it was well worth the effort because it ends up being a center piece in any kitchen thats used regularly, you are looking at the cutting board more then anything else in the kitchen (unless you stir alot of pasta or stirfry). At least, if you want all your fingers.. plus its just gross to think of stuff being rancid inside of the deep scratches that never seem to wash out.
this video specifically highlights out its good at dealing with 'clogging' material surfaces.
*be sure to use a nylon brush and good soap and warm water to clean em out when they are clogged up bad, it does help, you can clean very dirty gummed up things with a brush more so then running water. For this job you need to consider it more then the usual because it is really foul.