FOR ALMOST three years, more than 325,000 federal workers have been allowed to vary their hours or days of work as part of a congressionally directed experiment to test flexible work schedules in the bureaucracy. That experiment is about to end, and the Office of Personnel Management has decided to give the whole matter a closer look before installing "flexi-time" on a permanent basis.

In many private companies, the old 9-to-5 routine has become outmoded. One out of five workers now chooses to work either part-time or on a flexible schedule. Some specialists predict that half of the labor force will be flexing its work time by the next decade. Workers like the idea because they can dovetail working with family demands, avoid traffic jams and be more in charge of their time. Companies can benefit from improved worker productivity and reduced turnover. These benefits, however, are not automatic, and the federal experiment was not exactly a complete success.

In fact, there aren't many hard findings from the test. Partly that's because the project sponsors were already pretty much persuaded that flexible working schedules are a good thing, so they didn't worry unduly about the niceties of scientific evaluation. The study tells you, for example, whether a particular office stayed open longer hours, but it doesn't tell you whether that simply meant a shortage of help during peak hours of the day or whether any work at all in fact went on during the added hours. Workers, as you might guess, liked their new freedom. Managers--and other people trying to do business with the "flexing" offices--weren't always as pleased.

In some places the system simply went wild. Under the "maxi-flex" plan that some offices chose, workers could vary their working hours from day to day as long as they managed to show up on four out of five days. Unless a supervisor could prove that their choice of hours on a particular day was simply destroying the office's ability to function, the worker was required only to be present on three days each week during the "core hours" of 10 a.m. to 3 p.m. (with time out, of course, for lunch or for any sick leave or vacation time the worker might choose to schedule during this period). Other working hours could be sandwiched in any time between 6 a.m. and 8 p.m.--never mind if there was anyone there to supervise them or any work to be done while they were there.

Still the system worked well where managers and workers cooperated in seeing that their jobs got done and where the type of work lent itself to a staggered schedule. OPM plans to submit legislation to make flexible work schedules a permanent feature in the bureaucracy. It is, however, wisely taking the time to make sure that proper management controls are built in and that decisions about working schedules rest on more than a worker's preference for being at work when the boss is not.