My ds had a nursery uniform consisting of a polo shirt and tracksuit. He went five mornings a week. and he would change out of it as soon as he got home. I certainly didn't have a fresh uniform for him every day - it would be washed only when it got dirty (ie playdoh, paint, suncream).
This usually meant he'd have at most 3 fresh shirts a week, and the tracksuit would have one wash mid-week. Underwear and socks obviously daily changed, socks sometimes twice-daily.
As for his own clothes in the evening: t-shirts last 2 days at the most, as they tend to suffer from dinner and staleness. Shorts tend to last a bit longer and he has special gardening trousers (which he recognises as such) remain mucky for a week - what on earth would be the point of putting on a fresh pair every day for him get covered in dust/sand/grass stains.
He's always had a policy of changing into his at-home shorts (or slob shorts, as calls them) when he gets home from anywhere, same as his daddy, who wears casual to work (in an office) but still gets changed when he gets home.
He's starting school tomorrow and I shall follow the same policy (ie own clothes when he gets home). But he'll probably get fresh shirts every day, as they're the 'grown up' kind, which get grubby looking around the collar and cuffs easily.