I've got straight hair in a very short bob - quite fine in texture but quite a lot of it - and oily skin/scalp. I wash it every day with a silicone-free shampoo. My hair's in good condition and I only condition it once or twice a week. Now and again I give it a good old deep-cleanse with a clarifying shampoo. I'm sure I'd find daily hair washing and blow-drying a massive chore if I had long hair or had to do a lot of styling but the length and cut of mine means it's very quick to deal with.
Hair type and scalp type are a huge factor in how often your hair needs washing too - in stark contrast to me, my mum has very thick, wavy hair, which is also coloured, and a really dry scalp. She only washes her hair once a week these days, and even then it literally never looks like it needs it.
The more often you wash it, the more often it will need washing
It seems the more you wash, the more you need to wash it, which is why so many people claim "they need to do it every day".
This is a bit of a myth (and one that drives my hairdresser crazy, I recently discovered). It might be the case for some people, but it certainly won't be the case for everyone. It really depends on your hair type and on your natural, 'default' oil level. Some people have a naturally oily scalp, just like some people have naturally oily skin. You might 'restore its natural balance' with less washing, but if your 'natural balance' is oily, your hair will still be oily. If you've got very thick, curly hair then that oiliness is probably not a problem (or even beneficial) but if you've got fine, straight hair then any oiliness will be very noticeable.
Also, even if you don't have a particularly oily scalp, there are other lifestyle factors that affect your hair and have nothing to do with washing it too often. For example, If someone's hair is greasy or dirty because they work in a particular environment, or because their hair is constantly in contact with a moisturised/heavily made-up face, or because they use a lot of styling products, or touch their hair a lot, or get sweaty in the gym, washing it less often isn't going to fix that at all.