All what was written about fees is correct, but just for record (and maybe for novice users):
Blocks are "mined" by miners which do some calculations based on the given difficulty for some period of time. Difficulty is adjusted every 2000 blocks, just to have the average performance 1 block every 10 minutes. But, it is average speed, it does not mean transaction will be processed in max 10 minutes. Unfortunately we cannot tell when next block will be mined. For example in the current "evaluation period" we are statistically 20 blocks late and soon difficulty will be decreased by +- 1%.
As a consequence, you should be aware that it is possible to wait a long time for block and fee does not change anything. The risk is that if block is very late (it happens that we have 30, 40 minutes or 1h without block), fee which was sufficient 1 h ago, is not sufficient now, as your transaction will be removed from the 1st expected block as other users prepared lot of transactions with much higher fee.

I skip talking about low-fee transactions purged from mempool as we talk about high fees.