Carpentry and Woodworking - installing pre-hung doors

I'm installing split jam pre-hung (pre cased) doors in my basement project. I framed my rough openings 2" wider than the actual door size based on what I read on the door's packaging at the bix box store...in this case 26" for a 24" door. I went to test fit the door last night, I butted the hinge jam right up against it's trimmer (which is plumb) this resulted in about an inch gap between the outside of the strike jam and it's trimmer. Is this normal? It seems like a lot more space than I can fill with simple shims. How does everyone else deal with this much gap? I'm thinking of scabbing some pieces of 1x4 on the strike jam's trimmer stud which should reduce the gap enough that I can fill the rest with regular shims. Seems like I could have framed these opening 1/2 to 3/4" narrower and been fine.

A 26" rough opening would be just right provided you center the door in the opening. If the doors will be installed against the hinge side trimmer (with no shims), you'd make the RO smaller.

What I usually do, is nail 3 shims onto the hinge side near each of the hinge locations (butt ends all one direction) then come back and nail 3 more shims, one on top of each of the previous shims (butt ends in the opposite direction) checking them for plumb and sliding them in or out as needed to plumb the hinge side. Cut off all the shims flush with the wall thickness. Then install the door, nailing the hinge side first, levelling the top, and shim the latch side last with the space remaining.

If I am doing the framing, I make my RO only 1" wider, since I will "know" that my hinge side will be plumb, and jamb the door up against it, shimming the latch side as I square it in the hole.