I haven't seen a mention regarding the transmission line vs wavelenght?

Question

I haven't seen a mention regarding the transmission line vs wavelenght and the lambda/20 rule, so regarding the RF lines, shouldn't try to be all RF traces shorter than lambda/20?

PKusior · Accepted Answer

On behalf of Ian Collins: 
 Lambda / 20 is a rule that I guess permits one to almost ignore transmission line theory. So for instance for a 1 GHz signal, the wavelength is about 30 cm, and the Lambda / 20 is about 15 mm. 
 
 The transmission line will work, but in my experience it is better to consider anything higher than 100 MHz as a transmission line. 
 
 It is best to keep high frequency lines as short as possible, but not always practical.)