I would like to start develop my color negative films, never done this before.

Did my research with Tetenal because my store sells this. There is one thing that's not clear for me: how long can I reuse the solution, the values I have found are for 135 rolls.

So I have a Paterson sp-445 tank = 750ml
For the first four rolls, the development time is 8 minutes. This increases with one minute with the next four rolls ....
Could I safely say that 4 rolls = 4 sheets ?

At this time I have at least 2 roll 120mm and 16 sheet film

I know you can keep the solution for several weeks if preserved correctly, but with each development the strength will be less hense the longer development time.
But when do you need it to throw away, not when you see your negatives are bad ...

So still a bit confused.