I'm struggling to understand why you want to "get round" what seems to be a quite small amount of testing. So called "temporary" or "repair" pipework is a common reason for failure and I can see no reason why pipes being replaced should not be made to the same or better quality than the ones they are replacing. Of course if you only have two or three welds then you need to examine at least one, but I think that's reasonable as the welder won't have hundreds of welds to do to the same WPS, so you need to be mre careful.
If you're replacing a spool then this should also be presusre tested prior to installation.
Any repairs or replacements should be tot the same code as the original pipework. Some companies use the same edition of the code used for the original pipework for new pipework, some use the latest version.
My motto: Learn something new every day
Also: There's usually a good reason why everyone does it that way