Is The magical number 7 still valid?
As far as I recall, the &quot;magic&quot; of the number seven is that George Miller had to give a 1h-presentation while not having enough research on one particular topic to talk about this long. So he tried to connect unrelated lines of research, with the only connection between them being that they show cognitive limitations of similar magnitude (&quot;7+/-2 items&quot;). However, the comparison was not very serious and mostly rhetorical.
So I guess the short answer is: No it is not valid, and it has never really been.
Here is an short article that answers your question in more detail:

Cowan, N., Morey, C.C., &amp; Chen, Z. (2007). The legend of the magical number seven. In S. Della Sala (Ed.), Tall tales about the mind &amp; brain: Separating fact from fiction (pp. 45-59). Oxford, U.K.: Oxford University Press.

And here is Millers original article, it's actually fun to read:

Miller, G. A. (1956). &quot;The magical number seven, plus or minus two: Some limits on our capacity for processing information&quot;. Psychological Review 63 (2): 81–97.