Both, would be my recommendation.

By way of personal example why. I'd already covered much of what's in GF1 & 2 on other sites or sources prior to joining up with GT. Since joining, I've gone over, and concurrently interspersed, am still working through them out of thoroughness as recommended, but applying common sense in not labouring beyond discerning what's new, different, needs polish or I can benefit from increased situational awareness of nuance given where I am now.

Even so, generally it's a trudge frequently to be endured more than enjoyed in trying to keep my attention focussed on what is essentially rapid revision or reinforcement. So I spice it up with new songs, learning lead fills to songs I have already come to rythym grips with, and other new material presenting challenges beyond my current 'ken and skillset but within the parameter of accomplishable (with application) so my intellectual palette and motivation is regularly stimulated by tasting the sweet flavour of enjoyment in what I'm doing.

"All work and no play makes Jack a dull boy". Gives me a sense of elation and spurs motivation when I can hear the work pay off whenever I finally get a new riff or dyad fluid at tempo.