I agree with those above about digging the pennies.
I dig the zincolns currently for a couple of reasons and I'll provide as an example the public park I go to when I have only a couple hours to TH. I dig the pennies to 1) practice my pinpointing, recovery skills and to learn the ins and out of the metal detector better (BH Quick Draw Pro). I usually recover ~ 70% of my coins without digging a hole, a technique where I use a sturdy knife as a probe to locate the coins, make a small slit and pop them out (I learned this method when I used to TH with my parents in the 70/80s when there were no handheld pinpointers). It saves a lot of time over digging holes and saves the grass when the ground is dry. By practicing these TH techniques in a public park, when I go to private property I know how to leave as small as possible a trace of digging. The second reason for digging pennies is because most days I don’t find anything interesting except for them (and clad coins). I still consider myself a newbie and while I would love to find silver, wheats and older coins every outing, some days just beating the current month's record for the quantity in a day of clad is enough to keep me coming back for more detecting the next time. As was wisely said before, this is a hobby and if you don’t find ways to make it fun, you will likely leave the hobby. In this particular park that I was told was “hunted out” I am averaging about 40 coins each outing in a couple of hours of hunting. I have pulled 500 coins out of that park in 3 months, including a mercury dime and wheat penny. That is the great thing about this hobby: you never know what you will dig, there always is an opportunity to learn something new, and it is good exercise.