I seem to always end up making 5-8 personas in any business I work for. Sometimes we end up with more, but rarely (if ever) less. I love using personas and think they're an invaluable tool...but I sometimes wonder if things could not just be simplified? Could we have just 2 personas - one for each extreme?
For example: One power user who expects a lot from the product and knows how to use it. Then one novice who is terrible at computing and doesn't understand the product.
From that point onward if you try to cater to both you'd find a happy middle that serves your average user.
I'd be interested to know if anyone has tried this or knows of any good arguments for and against a small persona sample please :)
The two personas that you suggest represent the two extremes of a specific scale - the skill level scale. In reality we deal with many more scales that affect the design - goals, motivation, computer literacy, general education level, domain level expertise, frequency of use etc. That without going into domain-specific scales. For some products this will be the number of children, for others - annual income, daily mileage, workout routine, dietary preferences, state of health, shoe size or favorite music style. Extremely focused, small one-trick apps may have very few scales or maybe even just the one that you suggested. Others have many scales at once, with complex correlation levels between the different scales.
So no, I don't think that there's a universal minimum viable amount of personas :).
As a side note - there's also the approach that says that it's best to provide an optimal experience to some of your users than to design for the (mythical) average user, where noone ends up getting the perfect experience.
Yes, there is. It is based on how many different types of users/roles that you want to cater for, and that is based on how many different types of behaviours that are either mutually exclusive or has enough difference to impact on the design of the application.
If you answer no then it feels like you can go down a rabbit-hole where you create personas for people and behaviour that don't exist, which is then just doing UX for the sake of doing UX.