Do you increase and decrease it depending on how quickly you want the transaction to be processed or how big or small the transactions value is? Do you use a fixed amount for transactions?
As mentioned by Charles-Tim, fees are always dynamic and you should always look at mempool.space to get the best fee.
It doesn't matter with it is a big value or small. Transaction size doesn't depend on the value
It depends on how many people are transferring at that time, as there is a limit amount of space for transactions in a block.
If you are not in hurry, you can use a lower fee than recommended for the next block