To be clear here, I'm fixing film, not paper.
It was my understanding that people tended to reuse fixer. I am VERY new to film processing so am learning. The directions that taught me said to re-use fixer. My first gallon of fixer (Kodafix) was used around 2.5 months processing 15 rolls or more. I was just practicing with that gallon and now am starting off with a new supply of Ilford Rapid Fixer. I was going to dilute the entire 1 liter of fluid, and then use it for as long as possible, hopefully for 2-3 months, assuming that the fixer was not used up by film processing.
Then I read that Ilford gives diluted solutions a shelf life of only 7 days. It says that directly on the label on the bottle!
I hope readers can understand why I am so confused.
I did not want to use Kodafix again because that is a hardening fixer.
It seems like an enormous waste to use fixer only once. Am I wrong?
I've highlighted part of your problem.
For film, you need to have at least two bottles.
One bottle is the concentrated stock solution that you purchased from the retailer.
The second bottle is the container you are going to use for working solution - in my case I use a bottle that is 1.25 litre in size.
What you do is you take your empty working strength bottle and mix up enough working strength fixer to fill it. In the case of my bottle, I take 0.25 litres of the concentrated stock from the Ilford bottle and add it to 1.0 litre of water - together they fill my 1.25 litre working strength fixer bottle.
This leaves me with an Ilford bottle that is partly filled with concentrated stock fixer and my completely filled 1.25 litre working strength fixer bottle.
The working solution fixer comfortably fixes 16 or more rolls - I check the activity with regular clip tests. In between uses, the 1.25 litre working strength fixer bottle remains filled and tightly capped.
When the working solution has fixed all the rolls that it is going to fix, I take the solution to my friends who recycle the silver, clean out the bottle, and make new working strength fixer using more of the concentrated stock from the Ilford bottle.
If I am concerned with how long the Ilford bottle remains partly filled with concentrate, I will sometimes decant the remaining stock to a smaller, completely filled replacement bottle.