A distribution such as lognormal is likely to be more useful when you expect that underlying quantities are composed multiplicatively. This seems likely for habitable planet estimates, where the underlying operations are probably something like “filters” that each remove some fraction of planets according to various criteria.
Normal distributions are more useful for underlying quantities that you expect to be more “additive”.
If you have good reason to expect a mixture of these, or some other type of aggregation, then you would likely be better off using some other distribution entirely.
A distribution such as lognormal is likely to be more useful when you expect that underlying quantities are composed multiplicatively. This seems likely for habitable planet estimates, where the underlying operations are probably something like “filters” that each remove some fraction of planets according to various criteria.
Normal distributions are more useful for underlying quantities that you expect to be more “additive”.
If you have good reason to expect a mixture of these, or some other type of aggregation, then you would likely be better off using some other distribution entirely.