When do you buy your clothes?

When do you buy your clothes? Do you make a plan on buying your clothes  like to buy them on sale twice a year? or do you buy when you want?
In our case, we buy clothes when we "need".
I know the definition of "necessity" is very vague.

Yuki changed his pajamas into for summer. Last summer the pajamas had no problem. But this season, he feels itchy in the pajamas. Did I tell you? His skin is sensitive and he goes to a skin clinic regularly. He tries to avoid from wearing polyester clothes directly on his body. But some clothes are polyester ones, because he likes the design. The pajamas were polyester ones, but he liked the design, and it didn't cause any problem until last summer.
Probably getting old makes his skin more sensitive.
So I bought new ones on Net.

The other day I attended a meeting. It was a cool or cold day. So I thought which I should wear , a hard shirt or a soft shirt.  A hard shirt means that I have to wash it by hands and iron, a soft shirt means that I don't need any special care.
It was not so formal meeting, so I put on a soft shirt. In winter I often wore it but always I put something on it. I had never noticed that it had hair balls on the sleeves before I wore it alone. I was very embarrassed, though I knew on one noticed it. As soon as I came back home, I order a similar one on the Net, though the next time I wear it will be this winter.

Well, I told this story to Yuki.
Yuki said "I had same situation. The other day I went to Tokyo on business by Shinkasen, I noticed that the black of my pans faded. I was embarrassed".
I said to him "why you should wear your business suit?"
He said it was not so formal, so it was OK to wear casual "uniquro" pants.
So we went to uniquro to buy new ones. I don't know when he wears them. Because the fade pants are still useful.