You don't replace for no reason
Brother of The Benz, Johnson.
Johnson, there is no set frequency for replacing ignition components.
When one fails replace it.
The exception being, if you have to do major disassembling to get to a component and other ignition items are removed at that time, you might replace all of the items removed to gain access to the problem part, thus saving double labor at a different time. This keep everything fresh at the same time too.
As for my 103983 engine with 176,000 miles and still on the original ignition system, for this reliability, I have no answer. Just plain old luck.
My spark plugs are a different story.
Using "Copper Core" Champion RS9YC at $0.99 each;I keep rotating 2 sets.
I remove and replace with the alternate set every 7-8,000 miles.
These are the eyes of the engine. The plugs tell you what is happenning in the combustin chamber.
With the fresh set properly gapped at 0.032 inches, my engine never misses a beat and I am aware of what's happenning.
Your misfortune has to turn around soon, Johnson. Or your eventually going to have the best old Benz rolling.
I replace the fuel filter per the maintaince schedule.
I ALWAYS buy my fuel from a major refinner and a filling station that pumps a lot of gas, thus their tanks are clean.
My old tub has never drank anything less than posted 92+ octane fuel; To me it's too risky.
Happy Trails Beep Beep from The Spiderman in Houston!!!