Try it a few times and see what happens in your tank. I can predict something based on a theoretical scenario but it may never come to pass for your particular configuration. Water changes remove organic waste. Organic waste decays and produces ammonia. Theoretically, if the waste isn't removed, the ammonia production can be a contributory agent in BGA inducement for example. However, depending on your lighting, filtration, fish load , temperature, CO2, plant load as well as the combined metabolic rates of the plants in your tank, perhaps nothing happens or perhaps you have an algae outbreak. Check it out and then you'll know.
I tried that before, only change the water every two weeks and its not a good idea soon the tank went crazy with algae and I had to do two changes a week for 2/3 weeks to get it back on track. But every tank is different I guess!