I had a big bag of hickory chunks (about 30 lbs) that were mostly 3x3, 2x4, 4x3, variety of sizes. I would split the chunks into 1x2 or 1x1, 1x3 chunks. I say had I used the last chunks on last smoke.
When I start the smoke, I start with soaked chips, about 1/4 cup, once the smoke starts I add 2 chunks, I wait till the smoke is almost completely gone, then just run chunks from that point on. If the smoke doesn't keep going when I add a couple of chunks, just adds some chips and it will start the chunks smoldering. I have tried both dry and wet chunks and there doesn't seem to be much difference.
One thing, I am now starting my smoke about the last 20 minutes of preheat, I want a bed of ash in the tray. It seems that when the chips or chunks are first dumped into a clean tray they burn dirty smoke longer, which is imparting a creosote flavor. The ash seems to help the chips and chunks to catch just enough to smolder rather than start burning. (This concept is only in trial mode, not certain yet about the ash thing.)