"As plan audits have uncovered more and more payment errors, many plans have acted as if no time limits or other restrictions applied to their repayment demands.... [P]lan fiduciaries can consider the following steps to improve their chances of prevailing in these suits: [1] Make sure that plans have specific provisions for recouping overpayments. [2] Give the payee the opportunity to argue that the payment is correct under ERISA's claims and appeals procedures.... [3] Do self-audits regularly and if a lawsuit seems necessary, file it promptly. [4] Pay attention when retirees call to question whether they are receiving the right payments." [Pharmacia Corp. Supp. Pension Plan v. Weldon, No. 4:14CV1498 (E.D. Mo. Aug. 24, 2015)]