I have all the skills, because I want to be able to make everything in game. The only effect that has is a 715 percent time penalty on learning new ones. While that sounds quite awful, it's really not that bad - by spending favour points, I can still reduce times quite a bit, and I don't really need to learn each new skill as soon as it appears.
Even while I was still working on a large number of existing skills, some of those took very long. But there's so much to do in game that you don't really need to learn all the skills at once. I found spacing them out quite nice, so I could experiment with them one by one, rather than having a bunch and not knowing what to do with them.
To give you an idea: I started playing Glitch "full time" in May... I probably had only learned a couple of skills from back when I joined in October of last year and just today I finished learning ALL the skills. So it will take you some months to learn it all, but its doable.
I pretty much was learning ALL THE TIME (Glitch HQ app and Glitch Academy for some help) as well as spending my last few months donating for favor points like a crazy lady. :D
Good luck on your Quest to become an edumacated Glitch!
I refuse to learn every skill. I'm very non-completionist about Glitch. As a result, I was able to learn and unlearn the Master Gardening and PM3 skills (starting from not having any Croppery skills at all) in less time that some glitches took to learn just one of them. I unlearned them because they weren't useful enough to my play style, but I had the ability to learn them fast and wasn't wanting anything else so checked them out. I have an 80% learning penalty but would really like to trim it down further.