You are right - albeit for the wrong reasons - it is difficult for the lay person [*] to decipher what the infection rate is.
As such the infection figures presented on that Caronavirus Worldometer site can, at best, be broadly indicative but in the cases of some countries, it could easily be quite wide off the mark. So that they "forgot" to do the Saturday morning update is the least of the data veracity limitation; it's that they don't know what they don't know that is the limiting statistical parameter.
[*] Actually, it is impossible, because we have no way of knowing how many people get infected and are totally asymptomatic or have mild symptoms and who therefore don't show up in the data. And not just impossible for the lay person, but even for statisticians and medical specialists.
