Yes, five days between waterings is too long and your plant is telling you so by drooping. A good deep watering to run off every third day or so would be much better for your plants. Roots will not expand into dry soil , nor are nutrients available. Try to maintain an even moisture that is damp, but not wet. This may take some juggling and experimentation, but once mastered will become the easiest aspect to control during any grow. Since you are noticing how light the pots have become, you will eventually learn what the appropriate weight of a moist pot feels like. Moisture levels depend on many things; temps, air flow, your individual plants needs for water, the absorbency and water holding capacity of your substrate being just a few, with plant size obviously being the main factor. Letting the soil dry right out also increases the risk of your soil becoming "hydro phobic" whereby the water just runs straight through the pot with very little being absorbed. In that situation it can pay to give water in staggered doses. By this I mean, say you determine that you think your plant could do with 2 litres of water and rather than giving it all at once, give 500ml every half hour or so before giving the next doses. This way, over two hours and four applications, your plants soil will soak up a bit more water each time she is "dosed". The staggered watering will allow for some water to be absorbed, and a little more each time, thereby swelling the soil slightly, meaning the subsequent applications of water will be "trapped" and more of it will be absorbed, rather than just running straight through the pot due to dry channels and a soil that is very dry and has become "water repellent" in the process.
Hope this helps,... Organoman.