Consecutive Serials With Gap

If you find consecutive notes in ending serial sequence 1, 2, 3, and 5, would you keep the 5? Finding that 4 to fill that gap, would be next to impossible. Any value in keeping that 5? I went through the stack of notes looking for the missing serial but did not find it so I am thinking of just dumping that 5.

This was my first attempt at note hunting. No fancy serial numbers but I found 5 groups of consecutives, most of 'em only two in a row.
Which brings up another question is two-in-a-row worth keeping? These are two-dollar bills.