I personally believe we should be evaluating DFTPP or BFB every 12 hour window. DFTPP ion ratios are important for me to maintain not only a tune, but a calibration. Inexperienced analysts will learn more about their systems with a proper daily evaluation like this. A CCV may pass beautifully, but I would be interested to know that DDT is starting to break down, or benzidine tailing is getting worse.
It can act as a preemptive warning that maintenance is coming due.
As mentioned, tune evaluations should be evaluated using full scan data.
The problem with one-size-fits all QC rules is that you can't always anticipate how a method is going to be used. I agree that the tune evaluation is a good learning tool, but its usefulness beyond that depends on the use case. I can see a lot of value for a lab that ran a lot of samples and ran them for a lot of analytes.
On the other hand, my last lab was open 24/5, and only ran 1-2 samples per day (we only had in-house GCs because but the desired turnaround time was "now.") Quite often we were only interested in phenol, cresols, and naphthalene.
So once 8270E came out:
If DDT looked great, I'd run my samples.
If DDT was starting to break down, I'd run my samples!
Now, if I knew that the next day I'd be running for the full 8270 list, checking for DDT was a good idea. But then again, my CCV already has compounds that are going to tell me whether I need to do maintenance.
I hope the other EPA methods allow flexibility based on project quality objectives... especially the method defined parameters. The cyanide method requires that you use a 1.0L reaction vessel. There are great distillation setups available commercially that use smaller glassware (and use less reagents, have a smaller footprint, are built more robustly than heating mantles, and are safer to use than traditional setups) and achieve identical results. But, nope, cyanide is an MDP - you aren't allowed to use them.