You can get a new Nozzle that is poor right out of the box. Way in the past I bought 25 Monark Nozzles and one of them was very poor. I would not have known that without pop testing them and of course I balanced them.
No matter what part of the Engine you are working on you should be trying to keep it within the factory specs because that is were it is going to work best.
If you have other vehicles the time issue is just an inconvenience.
How to Rebuild Injectors
vincewaldon.com - HOW-TO: Rebuild Diesel IDI Injectors
Reasons to do-it-yourself is to gain knowledge and save money or have a choice what quality parts go on your vehicle. And yes sometimes you screw up and your skill levels get severely tested. But, it is the long game where you are building experience and knowledge that will be useful in the future.
Example on my Van I failed an emissions test with too much NOX and too much CO. I could replace parts but had no way to know what would work. If I took it to someplace it was going to be hundreds of dollars for testing and fixing.
I spent close to $200 for an CO analyzer. I figured that while I was still spending hundreds of dollars at the end I would have the Analyzer left over for other jobs.
Got on the internet and looked up stuff that would cause my problem and one of them was the O2 sensor ($18 for a new Bosch). I bought a new one and tested with the CO analyzer and I found out the O2 sensor fixed the issue. The defective O2 sensor was a Denso one. Won't by a Denso again.
The side story to this is I already had CO analyzer from back in the 1970's (analog meter) but I could not remember how to calibrate it and no more instructions. The new one is digital.
As it turned out the Digital one is made by a different company but it looked similar. I wrote to that company and found out the bought out the old company and they sent me instructions for the old CO Analyzer which still functions fine. Of course the analog reading is not as fine as the digital.