An asset can look correct in its source application and still fail after import into Unity. Treat texture budget as a translation problem between tools, with decoded GPU memory and maximum resolution checked on both sides.
For Unity, check color space, channel packing, texture resolution, and shader assumptions as one system. A texture budget pass should set a measurable budget and explain any visible compromise.
Set limits for GPU memory, maximum resolution, mip behavior, channel packing, and the number of unique texture sets. Apply this texture budget guidance to the actual Unity delivery path.