(Dave and I were typing same time. I agree 100% as you can see) With any buttplate inlet, sawing the buttstock to profile and then using a spokeshave to prep the surface before inletting helps a lot. Trying to inlet a buttplate onto a huge square buttstock causes problems for me. I sometimes used to find myself inletting the buttplate down into a hole. Same thing for entry thimbles- prepping the surface by pre-shaping it sure saves time and mistakes.
I find a few more challenges with buttplates in general. First is getting that tang to stay lined up with the comb line and not dip down at the front. I put a straightedge on it now and again. If you've cut your blank close to finish profile, or are using a precarve, there's no room for letting it get tilted and fixing it.
If the buttplate tang is simple and is narrower at the tip than at the base, and you find you have to scootch it forward, no problems. Otherwise it has to be inletted straight down, then you can bend the heel and "foot" to fit the rest. Assuming it's soft brass, that is.
Sometimes with all the tapping into place as you're trying to get a good fit of the tang and the heel and everything, the angle between the tang and the "foot" begins to open up. Before you start, you could cut a piece of stiff cardboard to exactly match the inside profile of the buttplate, right down the centerline of the buttplate and tang. Use this to check from time to time that you're not spreading the buttplate open.