In Mega Man 9, you have to do a bit of collecting. Mostly these Bolts that you use as a kind of currency to buy upgrades to make the game slightly easier. But collecting them is a pain, since they're kind of rare.
But you can tip the scales to your advantage (slightly).
First, you have to have completed Jewel Man's stage, so you have the Jewel Satellite.
Then go to Concrete Man's stage and stand right here (it's pretty close to the beginning), face left, and activate the Satellite
Now, birds will fly by and drop boulders which will break on the upper platform, and a chunk will fall into your shield. If a goodie falls out, it'll drop right on you for collection!
You'll get all kinds of drops here, and it just keeps going for as long as you want to stand around.
So how long you should stand there really just depends on how much stuff you want.