Cisco Systems (NASDAQ:CSCO) just doesn't know when to give up.

The networking giant keeps giving second chances to the owners of Norwegian teleconference specialist Tandberg -- and third, and fourth, and ...

The deadline for Cisco's latest buyout offer, which includes an ill-conceived boost to the price, had been extended three times in the hopes that at least 90% of shareholders would find the $3.4 billion price tag sweet enough.

Oh, and if this deadline should pass without any 90% agreement, it will not be extended again. That's a promise. On the other hand, Cisco reserves the right to waive the 90% ownership condition. Way to stand firm, guys.

It's just two more days, and the tally now stands at 84% -- but once again, Cisco is bending over backwards to get the deal done. And that sends the wrong message to future Cisco buyout targets, possibly raising prices and lengthening negotiations around any and all future deals.

Cisco CEO John Chambers is following in the footsteps of acquisition-hungry leaders like Larry Ellison of Oracle (NASDAQ:ORCL), who has been known to write a bigger check whenever his deals run into resistance. A far better role model would be Warren Buffett of Berkshire Hathaway (NYSE:BRK-B), who keeps negotiations behind closed doors and generally keeps his offers final. This is also how Walt Disney (NYSE:DIS) closed the deal with Marvel Entertainment (NYSE:MVL) recently, showing that Buffett isn't the only master of tight negotiations on Wall Street.

In all fairness, Chambers has generally walked in Buffett's shoes through the minefield of buyout negotiations in the past -- but that's exactly why I think it's dangerous to shift to a new track now. Imagine if Microsoft (NASDAQ:MSFT) had shown some patience and hammered out a real agreement with Yahoo! (NASDAQ:YHOO) before taking the matter public -- MicroHoo would be a reality today, for better and for worse. And Microsoft's acquisition team might still have some clout.

Walk away now and you might keep some of your hard-won deal-making credibility, John. But if you end up waiving the 90% requirement, you're going to look downright silly. Good luck with your next acquisition, in that case.

You're gonna need it.