My advice is to not do it half way, make sure your Realtor has proper signage and has marketed your open house through all of the different avenues (possible newspaper, their own website, MLS, Trulia....etc).
Make sure the home is in tip-top shape. I would not recommend doing two weeks in a row because you may just "split" the amount of people that would come one of those weeks. I would wait at least 4 weeks in between open houses. The best case is to hold one right after a price reduction (if you have one).
Even more important is the location of the property. If you are off the "beaten path" open houses may be a total waste of time. A homes visibility adds to open house sucess.
Hope this is helpful.
Open houses are a very "old school" way of marketing homes. They assume that your pre-qualified buyer has not yet hooked up with a real estate agent and is just randomly driving the streets looking for homes. It isn't done that way anymore.
Home buyers are on-line searching the real estate databases before they even connect with a pro. This is where you want to focus your largest marketing effors. Your home should be well prepared and staged, you should have great 35mm digital photographs (average cost $200 but most Realtors provide at no charge) and then those photos should be made into a slideshow that walks a potential buyer through the house. From foyer to living room to kitchen to dining room etc...however YOUR house is laid out. Do'nt have a photo of the kitchen followed by a photo of the back yard followed by a photo of the bedroom. Buyers will pass you by.
And no pictures is a death sentence for a sale. Buyers assume there is something wrong with the house.
So it's OK to have an open house and hope you get lucky there, but chances are it's just a way for your agent or whoever they appoint to make new real estate contacts and develop referrals. If you are going to have an open house it is always better to have it advertised on Realtor.com, in the local paper and in the MLS and to tie it in with neighbors. The more eyes the better. Best of luck.
If there were a lot of other open houses in the area and it is not an inconvenience to your family, I see no problem with holding open house two weeks in a row to capture some of that traffic. However, any open house held should be done properly with optimum signage, posted notice on all real estate websites of dates and times, consumer handouts, etc.. Insofar as good traffic is concerned, that would depend upon market conditions for your locale, weather and time of the year and would best be answered by your agent.
Best of luck,
If your home is located in a location that makes it visible and easily accessed, and if it's curb appeal will attract interest, you should consider having regular open houses. "Regular" open houses, doesn't necessarily mean having one every week but monthly or twice monthly would not be excessive.
Our recommendation is to not lose sight of your personal needs. Preparing a home for an open house can be a lot of work and an inconvenience. Basing these activities on your family's schedule and making them convenient for you should be a primary concern. One that will go a long way to ease the stress of selling.
As to traffic; the more the merrier for the agent doing the open house who gets prospective buyers.