Running Ghost Cartels at the moment and, when plotting out the calendar of events for my notes, I noticed that this is a *very* fast paced and intense campaign; the karma is going to be flowing fast and freely, but the problem with the pacing is that there isn't any time to train. Skill advancement takes so bloody long that I find it unlikely that any of my PCs will want to step down for a while for a weeks-long training regimen, either in or out of character. Plus, there are such things as on-the-job training and learning by doing.

Thus, asking for help with formulating a house rule for on the job training; I have just two requirements that I've been trying to keep in mind, personally:
1. It should supplement the regular training rules, not replace them--i.e. I want this to be a choice between taking time off to train as the more efficient option, versus the on-the-job training, which will be less efficient, but doesn't require downtime.
2. A minimum of bookkeeping.

One idea that I've had but am thus far dissatisfied with:
Each time that a character beats a threshold with a skill that they've been training with at least one net hit, they may immediately make an Intuition + (skill) test, with a threshold equal to the skill rating +1; if they succeed, that then counts as one hit on the training test.

Not happy with this, and looking for suggestions.

I've had a similar thing come up in a Mage: the Ascension campaign, where learning new Spheres of magic tends to take in-game months at least. Which sucks if stories are fast-paced and follow up quickly. After a while players had a pipeline of 2-4 Spheres in XP waiting, and I had to do something. I ended up throwing out the cost, although that doesn't satisfy entirely either.

In SR, it's doable to justify high-speed training of nonmagical skills if you can train in VR; you can go right ahead to the difficult, dangerous, expensive parts in the simulation without risking injury or loss of dangerous equipment. It's a bit handwavy, but it's an excuse at least.

I don't use training times at all. Period.
Characters are supposed to be practicing the skills they're going to grab next during their off-screen time.
Now, that saves us from bookkeeping.

Your house rule add many tests to a game with enough tests - you could modify it a little by making a mark every time someone use a skill (I'd make failures count too) against a Hard+ threshold in a scene. The next time they make a skill learning test (Maybe give them a free one at the end of each story arch) they get the number of marks as a positive modifier for the test of the skill.

Am I missing a rule? I fail to find mention of training time for skills mentioned anywhere.

OK, page 270.

I think that you should be able to spend karma at least as fast as you get it.. it's no use if it just keeps piling up without time to spend it. A restriction I tend to use is that you can upgrade any ability only once per mission/adventure.

It's not realistic, but I think it works better for the game.

You could make an exception for some skills the characters are heavily using through the adventure, so long as they already have said skills at a rating of at least 1.

You can also cut the time interval in half for those learning skill checks mentioned above, but you also up the chance of a glitch (1's & 2's instead of just 1's). It's in the SR4a book somewhere, and IIRC it's gamemaster's discretion as well (some things just can't be hurried).

I agree with Fatum. In a 4 hour game window each week, with about an hour probably devoted to mere seconds of combat, I just take it on good faith the "characters" are training in AR, VR, or someplace in the meat in their off time. I haven't used training rules in about 10 years once I got my brain wrapped around that idea, and have never had an issue since. Plus, as a player, it just sucks having to wait to spend all that righteous Karma you've scored. There are plenty of things player's have to "wait for" in the game already like obtaining gear they may need, or writing a program or formula, so I don't see a need to make them wait to be better Shadow runners. My approach has rubbed off on my group, and when other folks run a game using the Shadowrun system, they have forgone training times as well. Besides, asking for too much realism in a game with mystical ninjas running around with cyborgs fighting in a world with dragons is just plain silly.

I typically waive improvement times when purchasing with Karma, and use the training schedule for improvement without the expenditure of Karma, but that's unlikely to work with SR4's training times as written.

Personally, I ignore training time in all of my games, but we have a rule that you must actually be using the skill in game to level it. Yes, that means people will have to occasionally default a few times before they can learn a skill, but I figure that it's learning by trial and error. When we have periods of extended (in-game) downtime, I have them tell me what they were doing and we have a short (less than 5 minute) RP scene for each character to explain how they learned any new or usual skills. Downtime can also be used to add or remove benefits/defects to tweak characters and give extra karma where needed. (A good example is our gun bunny took a part time job at the gun shop to explain the sudden jump in his loyalty rating with the store owner.)

In all the game I've been in as a player, training time has been largely overlooked.

I think this has to do with a real lack of a 'downtime schedule' in shadowrun, and that many things can theoretically take up your whole day (availability tests, I'm looking at you), and its kind of unrealistic that people can't browse shadow-ebay for a gun AND hit up their gym/dojo at the same time when they aren't doing anything else. So i think most people just tend to throw those rules out the window.

My GM always did it the following way: If it is your first rank you need to do the training time otherwise you can raise it at your leisure.

When I GM, I tend to take 3 sessions to complete a mission, and then the next session is entirely downtime. Depending on the group, this ratio can change dramatically: my old group used to spend 3 sessions on downtime, and 1 doing a job to make the money to do stuff when the next downtime came around...which, when you think about it, is a lot more true-to-life for a professional criminal of the "works once a month" sort.