Adding An Extra Pass Between Roughing and Detail for 3D Projects

I am attempting a large (24" x 24") 3D carving which causes a very long detail pass of 13+ hours using a 1/8 ballnose finish and a 1/4 endmill roughing. Is there any way to set up a 3rd pass that might cut down on that overall time? I was thinking 1/4 endmill roughing, 1/4 ballnose midstep, and a 1/8 ballnose detail. When I do original basic 2D carvings I am able to create duplicate file copies and delete pieces that look just fine with the roughing pass and keep only the portions that need the finer detail in a copied file. This normally cuts off a significant portion of the cutting time (sometimes by at least half) but this is not an option in the 3D. I was thinking of trying to do something similar and have it do 1/4 endmill roughing and 1/4 ballnose detail, then open a copied file with it listed as a 1/4 ballnose roughing and 1/8 ballnose detail, (And on the copied file just skip straight to the detail pass since the 1/4 ballnose “roughing” pass had already been completed on the original file) but I am unable to add the 1/4 ballnose bit to the roughing pass options. Lengthy question but I would appreciate any help!

Have been thinking about the same thing, have not tried any of these ideas, but perhaps my ideas might trigger an approach that would work.
Run the roughing pass with high step over (40 0r 60%) and largish depth of cut.
Run the cut again with smaller step over and smaller depth of cut,
perhaps with Z set a little lower (1 or 2mm less)
Use a machinists 1-2-3 (or equal) block to set Z. You can use shims to maintain repeatability and accuracy.
My thinking is that if we can get the roughing pass as close as possible to the detail pass, we can crank up the detail feed rate thus speeding up the carve, you can also increase the plunge rate quite a bit on a 1/8" tapered ball bit.
I do not do chip calcs, but watch the chips based on many years of router use, If getting dust and or burn marks either step up the feed rate, or slow down the spindle rpm.

Adding A 3rd pass will not reduce the movement of the finishing pass.
There are multiple other sofftwares that have been in the 3d game years (some a decade plus) ahead of Easel and they do not do this.
Doing a bit 3d in the manner explained would not improve carve times.

This shows some tips to improve the finishing pass that do actually work to cut down the time.