Male betta fish do not make bubble nests if the conditions of their environment are not satisfactory or if they are not ready to spawn. Producing bubble nests is a natural behavior for male betta fish and is not necessarily done in readiness for spawning.
Healthy male betta fish tend to produce more bubble nests, but there is no typical amount of production. For example, some make bubble nests frequently, such as daily or weekly, others only every couple of months and some will only produce a bubble nest once a year.
Bubble nests are blown in readiness for the female to lay her eggs. After spawning, the male places the eggs in the bubbles and guards them until they hatch. In captivity, bubble nests are often made even when spawning is not about to occur and can show that the fish is happy and healthy. The formation of bubble nests may not occur if the fish finds the conditions of the tank, such as the pH level of the water or strength of filtration system, unfavorable.