Adding additional context to the number of charges, I've found that fissures on mother lode asteroids in rocky rings behave differently than those in icy rings (that said, been a while since I've been void opal mining). I always start at the lowest strength fissure with the highest charge possible. After that first charge is set I decide which strength fissure works best next. To make it easier I try to pick one that allows me to either full strength or half strength. Typically I can crack a rock with 2 charges in icy rings, but in rocky rings I find the charge strength more variable and might use 2-5 charges.
To validate what the other posters have said, no matter how good you are at hitting the blue line and never go into the red it's random in getting the maximum yield exceeded message. However, again like other have said, the only thing that matters is how many chunks you gets. I think that it's possible fissure strength and charge placement might affect how many resource chunks you get, but that's just a guess and I quite offen get 12-15 chunks without taken in those considerations at all.