Yeah, the Focus grind would be insane if the intention is to max them all out, and that seems to be how a lot of the Warframe community is approaching it (judging from /r/Warframe).
I’m choosing to look at it more like prestige/paragon/whatever levels that will always give me some progress bar to increase, no matter how long I play. My impression is that this is the intent of the system, but I could be wrong on that. As it is, I focused on grinding until I had enough for Energy Dash and now I’m good. I’ll just let it come in as it comes in. If they end up bumping up the rate later, then fantastic. If not… well, thus far there’s nothing gated for me, I’m already doing the content. So no worries. Besides, the majority of the items in the trees are far, far, from “must have” type abilities.
I do wish they’d eliminate those damn Convergence orbs, though. I get that they were placed there to deal with AFK focus farmers, but that doesn’t seem necessary as long as there’s a daily standing cap. I don’t like that in order to gain focus at any sort of decent rate, you either need to cheese stealth or play a couple specific maps with specific warframes in order to grind it out. I’m good with it taking ages to complete all the nodes, but I would like to make progress just through normal play.