Hmm, so I basically need other custom value resistors to make the custom value resistor I need. That's helpful. 10-turn trimmer pot it is.
The values specified are available. It's more for when you need a non-adjustable resistor to replace something unusual in a piece of equipment. You're not getting them in carbon comp, you've moved up to RN55 or some other tighter series.
For example, I have a device that has a custom-wound 61.9Ω sense resistor. Using a trimpot would be difficult because of the wattage, and other factors about how the device operates. But, I can easily get a 60.4Ω and a 1.5Ω for under a buck. They're tight tolerance with low PPM, no pesky wipers to get oxidized or move.
I work mostly in digital or audio analog so values outside of the classic standards are rare or at least not high power requirements. If a sealed 10-turn trimmer get oxidized or move, then someone fucked with it. I don't tend to build audio power amps or anything like that so I think I'm fine with off-the-shelf multi-pack carbon film or metal film junk from chinkland for most projects.
PPMs- I'm not Marco Reps so I don't have a lot of need for PPMs or get excited about precision metrology. Ballpark suits me well enough.
I understand there are certain fields that don't need that kind of precision.
I'm mostly working with test equipment where that 7.026M resistor in the voltage divider circuit is already fighting the 3% of the movement of the meter itself, so having exact replacements is more of a necessity. My stuff gets beat around and is point-to-point, it's just easier to use fixed values that are meant to be connected with leads.