Sometimes when I withdraw BTC to my wallet, I set really low fees like 50-70 satoshi per byte and wait for weeks, because I'm not going to spend those coins in the near future anyway. I think it's a good way to save a bit of money, because if you look back, you might realize that your fees have added up to a big amount in USD value, while it wasn't always necessary to get those coins confirmed asap.
So, do you use low fees, or always want to get confirmation in a next few blocks?
to send bitcoin from wallet to market or wherever I use a very relative payment cost, when bitcoin price is very expensive and when the transaction is very solid then I will give an expensive shipping cost in order to quickly get to. but when the market conditions calm not too crowded I can use a small fee.
https://blockchain.info/unconfirmed-transactionsthere you can see the condition of all transactions from bitcoin.