My kids range from 19 down to bub, so I have had plenty of experience with kids getting into mischief. Some of mine were masters between ages of 2 to 7.
Personality is the biggest factor and then of course dad being away and than there are the other triggers being bored or just seeing the opportunity and it being just to hard to resist.
Kids brain are still learning about consequences so they may not be at the stage where they even think about at the moment a opportunity arises. They say it takes until we are in our 20's for this to fully develop. Every child develops at different rates. Boys often take longer than girls. So keep going with the consequences and they will learn in time.
On what they should be and how strong well that is really up to you as you are the only one who knows your kids. I know what consequence I give dd3 wouldn't even register to dd2. And dd2 would crush dd3.
Right now ds3 is driving me batty.