From what I am gathering based on this question and this question it seems that I am better off not trying to clear arrays or mappings. As the documentation on mappings indicates every possible key is initialized upon declaration and mapped to zero values.
I've taken Nick Johnson's advice from the first Q and I'm keeping an array count which I'm using to iterate through the arrays (and mappings) in lieu deleting the arrays. My question is whether there's anything to be gained by clearing out the values associated with keys which are storing data.
One mapping is from an address to a list of structs, the other is from an address to a struct. Am I correct in thinking that the gas cost of storing the data is spent when it is set and thus there is no additional value in trying to free up space by clearing the struct data out?