The smallest unit of Ethereum is called Gwei, not Sat. However, the value of Gwei, which is the gas required to send an Ethereum transaction, changes constantly depending on the state of the network. Currently, the value of gas required for an Ethereum transaction is 17 Gwei.
The value of Gwei ranges from 3 to 50 sometimes depending on the state of the network. Therefore, the required value of Ethereum varies according to the value of Gwei, and this necessarily leads to a difference in the value of the required gas according to the price of Ethereum as well.
Therefore, to reduce the transaction fee, you must constantly monitor the number of Gwei required for gas and choose the times when this value is low.
Right. Sats are for BTC but I think it's not its smallest form. I know there is still beyond it and I think its called milibit or minibit ,something like that. The transaction fees of all cryptos are not fixed but it changes depending on the activity of the network. If it's heavy loaded or congested then the fees are expected to rise but if it's the opposite, we can also experience to have a lower fees.
There is a site to check the fees of ETH, I think its called gas station. We can check the fees there before we transact if we want to save but based on my observation, ETH transaction fees are lesser on 12 to 1 am. It does make sense since many people are already asleep during these times.