config.txt - FTP time interval question

From the config.txt file:

Do clientraw FTP=Y //(set to Y for yes, N for no), uploads every 1 minute

FTP time interval=30                   //the interval between two upload of the clientraw.txt and custom file 

I’m confused about the meaning of the “FTP time interval.” In the example above, if clientraw is uploaded every minute, how often is the custom file uploaded?

obviously ignore the uploads every 1 minute
(I will fix that)