A chicken typically lays 1 egg every day, occasionally skipping days. Some breeds lay less, some lay more. Different breeds also lay different sizes and colors of eggs! If everyone is laying well, 3 hens should give you nearly 20 eggs a week.
However, many factors can cause a chicken to stop laying temporarily. The biggest factor is molting. Chickens naturally shed their feathers and grow new ones. This is stressful for them, and typically they stop laying during their molt. You can help them through it by providing more protein. I've had molts last a week or two, and other poor birds seemed to take ages! Other factors include diet, season, weather, stress, and more. Are they getting enough food and nutrients to produce eggs daily? Is there an extreme temp. fluctuation? Lots of unpleasant weather? Sometimes girls don't want to lay during poor weather conditions. Also the daylight hours; if they're not getting 12 hours of sunlight each day in the winter, they stop laying naturally until days grow longer again. Is there stress, such as poor living conditions, cramped space, or predators around?
These are all natural defense mechanisms; when food is short, nutrition is low, weather is harsh, predators are about, or days are short and cold, a hen doesn't want to produce offspring. So by providing a safe, controlled environment you can encourage them to continue laying year-round.
In regards to bad eggs; no home-grown chicken should rightfully lay 'bad eggs'. Healthy birds in clean conditions lay beautiful, nutritious eggs! Collect eggs daily to ensure freshness. Keep nesting boxes clean to avoid fecal contamination. Leave eggs are room temp and unwashed until ready to use. And if you're not sure how old the egg is, submerge it in water; OLD eggs will float, open those with caution! Fresh eggs will sink.