It is my undersatnding that k-mans experience is the current trend. The rule states that assets must be segregated as soon as reasonably possible, in no event will this time period exceed the "15 business day stuff". The DOL's position is that generally assets can be segregated within a few days of the payroll date.
I attended a 5500 workshop and we were advised that the DOL is going to start hammering this one hard. If the employer is concerned about increased administrative expenses assoicted with weekly, bi- weekly, etc. deposits, it was recommended that at a minimum the plan sponsor establish a seperate checking account under the Plan's name, segregate the assets immediately into the checking account and still continue to remit monthly deposits to the investment company out of the checking account.