I usually give myself a fixed amount of time or I'm never finished. Otherwise I'd be tweaking until the final horn sounds.

Things that have killed Bryce saves:

Extreme poses, bending an arm till the joint skin wrinkles up or bending an arm+clothing till it sticks inside the back or butt of the character. I know the camera won't see it but the engine still has to calculate how to render it.

Fancy props, especially those with transparencies. I tried horsefeathers posable mane and tail for the poser horse.once again any time the mane penetrated another object the file would not save. Don't stick something through something else, especially if it has transparency.

Degenerate faces, Melinneum Dragon LE won't work well in Bryce. supposedly there are open points in the mesh though I haven't tried to find them. Changing the flap angle on the wings can sometimes fix this.

Non PC imports, I've had trouble with Japanese poser files, imports made on Macs that violate PC naming conventions, Busted cob files with hidden geometries. If the material names are a page long or a single cup is 10Mb then something is wrong with the import.