In the old days, a bank customer usually had his choice of several tellers. He could note the length of each teller's line and try to guess which would move fastest.

Picking the right line was a lot like playing poker. The player with skill had an advantage, but luck played a far greater role. Canny customers avoided getting behind anybody carryng a bag, satchel, pouch or briefcase on the theory that such a person might be depositing 247 checks and picking up a $20,000 payroll. But on unlucky days, even skillful players guessed wrong and found themselves trapped in the slowest-moving line.

These days, banks have eliminiated the need for guessing. Everybody gets into a single line, and the person at the head of the line goes to the first available teller.

The new system benefits both the bank and its customers, and it can be put into effect with a minimum of expense. On the other hand, drive-in facilities are expensive, yet they are not as efficient as they should be.

Uncooperative customers slow up drive-in lines by waiting until they get right up to the teller before they begin writing out their tickets and checks. I suspect that most of them are well aware that their paper work should have been done elsewhere, but they just don't give a hoot.

A few may be unaware of the inconvenience they cause others; some people are like that, you know. You mean well but are oblivious to most of what goes on around them. It's not easy to get their attention.

However, two simple things could be done to speed up drive-in lines and thereby benefit both banks and their customers.A sign in every drive-in window should ask customers to have their paper work ready before they arrive at the window. And inside each teller's cage there should be a stack of politely worded reminders that say something on the order of, "To help us serve you more quickly, please complete all your deposit slips, checks, endorsements etc. before you reach the teller's window." When somebody holds up the line, the receipts or cash handed back to him should be accompanied by one of those notices.

The foregoing may cause some local bankers to consider forgiving me for my opposition to the $15 charge for Visa cards. Before they do anything so costs of doing business have made it necessary for me to stop giving out free advice. From now on I will have to begin charging $15 for each suggestion I make to bankers to help them improve their business. And, believe me, that modest fee will not even cover my out-of-pocket costs. I lose money on every suggestion I make, and it's only the volume that permits me to eke out a bare living. SILVER THREADS AMONG THE LEAD

Last week I wrote an item headed, "Let's Get The Lead Out." It was about the stubbornness with which newspapers now use lead where led is needed.

So two days ago we did it again. We said a former employee of the Hunt brothers is being sued by them "because of highly questionable circumstances that lead to his departure."

Thus far I have received only 18 clippings of a June 7 Metro story about a man who had been brought to the hospital with "a blond disease." We changed the n to an o as quickly as we could, but by that time our high-speed presses had spewed out a lot of newspapers. If you turn your head to sneeze you miss seeing a couple of hundred papers come down the chute. OF COURSE

Bob Batz reports that the number of overweight Americans has reached 12 million. "That's in round figures, of course." THESE MODERN TIMES

Herm Albright of the Perry Townshipp (Ind.) Weekly comments that most people have to work two jobs these days: one to pay the bills and the other to pay the interest. SWIFT COURIERS

Charlie McAleer mailed a letter from Wheaton to the American Legion office on 21st Street. Charlie's envelope was neatly typed and complete in every detail, including the correct ZIP code.

In only two days, his letter arrived in Waukesha, Wis., and in only seven days it was delivered to the American Legion in Washington.

Good work, gang. Next time, let's try an experiment. Let's eliminate Waukesha from the itinerary and see if we can cover the 12 miles in even less time. THE MALE ANIMAL

"It was a quiet week on television," says Bob Orben. "The top-rated show was a special from California: 30 minutes of Dolly Parton during the earthquake."