I have had sellers ask what incentive I have to sell the home within 30 days if they are obligated for 6 months? That's an easy one. I don't get paid until I sell the home! I want to feed my baby boys this month! I would rather a seller take a longer time with the vetting process than using the listing term to determine if I am a skilled agent. If, after plenty of due dilligence, they decide that I am their guy, than I commit to them and they to me. I am not a mass lister, and typically carry 4-8 listings at any one time. Committing the resources I do to the relatively few listings that I carry, I simply cannot risk them lapsing any sooner.
If I were to ever consider a shorter period, however, you can be certain that it would be tied to my list price.
I tend to think of listing prices in terms of how quickly the seller wants to sell, and that will drive the price to some extent.
The online "experts" who haven't been in the market for years, suggest that sellers list for 30 days to see what the realtors "are made of." Okay, if the price is real. But if the seller is unrealistic (as is OFTEN the case), 30 days won't get it done.
The sayings in this part of the world are, you should be the second wife and the third listing agent, because by then, the other parties are realistic.
There are some Realtors that prefer shorter listing periods so they can Re-List your home and it will show up as a "new" listing. This practice is called "churning" and is frowned upon by the Dept. of Justice because it deceives the public as to the actual number of days the property has been available for sale.
My research shows that in the majority of cases, selling residential real estate in the first 30 days will generally net the seller the most money. Conversely, the longer a listing remains on the market, the less the seller will net. The problem is really one of expectations. Sellers hate to see their equity evaporate, and many Realtors have a difficult time helping sellers be realistic about the actual selling price.
Of course, this quote always helps: "prediction is difficult, particulary about the future".
I don't ask for long listings, because the renewal process is a built in trigger to review price and strategy.
I would adjust according to the market, the property and the client. My goal is to have completed sales, and long listings contributed little to that goal in my recent personal experience. I have had a few that were hunky dory after an extension or two. Usually land , those can take a long time.