[Grml] grml daily builds

Hi I found the page that generates daily builds of unstable and stable grml, I notice that iso size can be exactly the same for 3 or 4 consecutive days so I suppose nothing was changed or added to the iso in those days, is this correct?. I might be wrong but I don't think there are devs coding new things or modifying old ones every single day. I suppose that the app which generates the daily isos do it automatically and it doesn't matter if something new was added or not, modified or not, it simply keeps doing daily isos non stop, correct?. Thanks in advance for any info.