As has been pointed out many times before the Park chain checker and similar ones have one somewhat valid purpose - a quick check of a chain in a shop situation where one does not have the time to crunch down with a ruler and peer at 1/32 graduations. Even then if I still worked in a shop and suspected the checker was overstating wear I would double-check with a ruler. I suspect most people have the tool because they feel it's more high-tech and cooler than a ruler.

Secondly, also discussed previously, it's best to leave the original lube on the chain for some time, as it seems to do at least as well as any off the shelf lube.

Finally, given the relatively low cost of a chain, cleaning (as in solvent dunk) weekly seems a waste of good riding time for questionable benefit. If you are not completely cleaning then you're just rinsing grit further in.