Survey of the art:
George O. Smith: "The Brain Machine" If you wore the helmet while reading a book, you knew the content of the book perfectly. You could not record the process, as your brain wasn't like someone else's, and you would get garbage. This was useful for learning facts, but you still had to practice how to put the facts together.
Academic subjects fall into two categories: Ones requiring brains, and ones requiring only scholarship. The BM helped learning the base facts, and so was great for scholarship subjects that are dominated by details, but was less helpful with subjects like math and art.
It was no help at all with motor skills.
Larry Niven's story "The Fourth Profession" has aliens coming with pills that give whole knowledge sets, using RNA. (yeah, hard to suspend disbelief) The RNA was tagged so that there was a corresponding 'forgetting' pill. The hero takes a pill that makes him a prophet, with the ability to do miracles. He can turn Water into fresh Blue Mountain Jamaican coffee. He dematerializes the forgetting pill...
A bunch of Heinlein stories make casual mention of hypnopaedia (learning in your sleep)
Christopher Anvil has his Interstellar Patrol agents getting local language through an overnight process with a helmut.
Simon Ilyarin in the Vorkosigan books has a chip in his head that allows him to recall everything. It gives him perfect memory as well as the ability to replay chunks of memory. No clue how it's indexed.
So you have to decide what a skill is:
If I download Electrician into my head...
... I know the relevant codes.
... Do I know the usual sequence for wiring a house?
... Do I have the feel for how tight to grip the wire strippers to take off the insulation without nicking the wire?
... Do I have the muscle memory to fold with wires up so they fit into the electrical box?
... Do I have the eye to look at a box of wire and know if there is enough wire for a 60 foot run to the heat pump. Can I tell 12 gauge from 14 gauge by picking it up?
... Do I have the trouble shooting skill to figure out the mistake with a 4 way switch (single light can can be turned on and off from 4 different places) that leaves the light on all the time.
I guess after this, I need to weigh in on answering the actual question:
I think it's barely possible that at some point we will get some for high speed knowledge implant. But I don't think it will be enough to make you a world expert. E.g. You will easily get 5000 grand master chess games, so you can readily compare your present board to what previous players did, but you still have to play thousands of games to become a GM. You can get all of music theory in a download, but you still have to train your ear to hear and your fingers to play. You will be able to know what an olympic quality marathon runner knows, but you will still need to run a lot before you win a race, and you may not be built to be a runner, may not have the major 12 spanning fingers of a Rachmaninov, may not have the interest to play 10,000 chess games.
There was an article in Scientific American some years ago claiming that it took about 10,000 hours to become world class at anything. That's 10,000 hours of well designed practice. Note that word 'about' Factor of 2 either way. And that didn't guarantee being world class, but was what most WC people seemed to end up doing. E.g. 10000 hours is necessary, but not sufficient.
So to become a decent pianist or chess player, 3 hours a day for 10 years. But it has to be good practice.
The article also defined what 'good' meant. Mostly stuff right at the edge of your ability. Practice of the old hat stuff kept it fresh in your mind, and maintained muscle memory (scales and finger exercises) Practice of the impossibly hard was just frustrating. So unless you pay close attention to what you are doing you could spend 6 hours a day to achieve 2 hours of good practice.
https://blogs.scientificamerican.com/guest-blog/too-hard-for-science-seeing-if-10000-hours-make-you-an-expert/ is a good starting point.