The standard characteristics of this method involve the system keeping track of the number of times a block is referenced in memory.
When the cache is full and requires more room the system will purge the item with the lowest reference frequency.
[1] The simplest method to employ an LFU algorithm is to assign a counter to every block that is loaded into the cache.
Due to how rapidly it was just accessed its counter has increased drastically even though it will not be used again for a decent amount of time.
[3] Moreover, new items that just entered the cache are subject to being removed very soon again, because they start with a low counter, even though they might be used very frequently after that.