Fleets (and ships!) do store fractional experience amounts, for use when more is gained. Ships used to get experience for destroying seekers. It was less than 1% each, but it was so much that it was ridiculous. This was patched out many, many Versions ago.
Asmala, it wouldn't take that long for MM to get the formula out of the code... I think it is safe to assume that Aaron writes code in clear fashion.
