The amount of eggs in a clutch will depend on the female budgie, each female will have a set number of eggs to lay. On average a full clutch will have 5 - 6 eggs.
It's important to discourage continued egg laying because that will have a negative impact on the female's health and as you have previously experienced with one of your finches, it can lead to egg binding which is a life threatening condition.
If your lone female is constantly laying eggs without being encouraged to do so and there are no nests on the cage, then chances are high that she is a chronic egg layer and the necessary measures must be taken in order to slow down and even put a stop to the egg production.
By getting fake, plastic eggs you can delay your female from starting another clutch but this will not be effective in the long run.
Reducing the daylight hours and the protein intake on your female could help in throwing her out of the egg laying mood. By placing your budgie on a different cage (no nests available) and moving the cage to different rooms can also be effective in terms of getting her out of breeding condition.
For the detailed information, check this link: https://talkbudgies.com/budgie-breedi...want-eggs.html
If after taking all of these measures you are still unable to break your budgie's egg laying cycle, then it would be best to discuss treatment options with your avian vet.