When you use a backlink checker, they check their own database to show the amount of backlinks, depending on the last time they crawled the website just like Google does it.
How many backlinks will show at any given time will depend on when the backlink checker has last crawled those sites. Some of the sites are well known and get crawled often, while others are less frequent and will take more time to show up.
NaturalWriter
How many backlinks will show at any given time will depend on when the backlink checker has last crawled those sites. Some of the sites are well known and get crawled often, while others are less frequent and will take more time to show up.