Also, suppose the transaction is not urgent (say changing BTC between own wallets or sending to a relative), can it be sent with very low fee? What's the worse that can happen - will the transcation get cancelled/not go through on the blockchain?
Not directly related, but you mention not urgent transaction. I noticed that usually mempool gets fuller towards end of the week and empty over weekends. So cheapest day to send a transaction is Sunday. Or the fastest day to send cheap transaction.
You made me curious about transaction fee in different days of week.
I calculated the average transaction fee for different days of the week in the past three months. (Raw data from https://bitinfocharts.com/)
Monday: 0.70 $
Tuesday: 0.70 $
Wednesday: 0.71 $
Thursday: 0.71 $
Friday: 0.74 $
Saturday: 0.63 $
Sunday: 0.57 $
You were right. I hadn't ever noticed this.
LOL well I never went to check exact numbers but saw it just by looking at mempool graphs. And we of course usually look at mempool when is more full then usually
At those times difference is for sure bigger.