the "30 levels in 3 months" thing drives me crazy, so I'd love to see ideas for handling it.
This has long been an obsession of mine. And I will go on a long diggression on it in this post, before betting back to the OP in a seperate post.
The defualt response is, don't worry about it. A lot of campaings don't really track calender time, and its all in the abstract.
Another is to treat it purely as a metagame issue. So at a natural breaking point, the DM (along with the players) just sort of agree that a year or so passes.
Then there are mechanical approaches. Basically the current RAW, is a the "day here and there" approach. So some time is spent traveling, making stuff, buying stuff...but with the current raw, this won't be much time.
In 1E, you had much slower healing and harder traveling, and this could take more time.
You also had training, (though groups often ignored it) which can require days or weeks. In my 2E years, I went farther, and had a rule of a minimum 10days per level per level. I.e. A 5th level charecter had to be at that level for at least 50 days.
The problem with these approaches is that they are not that flexible, and may still not chew up as much time as the metagame approach, or if you do have them chew up a lot of time, they get really inflexible.
I have tried XP for downtime as a sweetner. This works pretty well, but you have to be carefull or charecters will start tracking by the day. An alternate on this is XP for gold spent (this goes back to XP for gold in 1E) which can also take time. These both can be more flexible.
This is my current house rule:
Rest and Readiness: To fully recover with an extended rest requires one Rest and Readiness (R&R) point (otherwise at least a few days are needed). To level requires one full day off and three R&R points. You regain R&R points during down-time in which you are not adventuring (or otherwise not using powers or rituals (much)). The amount regained depends on the amount of time and related expenses. The later are generally spent as appropriate for the character and go beyond basic living expenses. Characters in higher tiers need to spend more. You must gain one or more levels in between R&R periods:
Time Cost (H/P/E) R & R Points gained
1 Week 100gp/200gp/400gp 3 R&R points
1 Month 200gp/400gp/800gp 6 R&R points
6 Months 400gp/800gp/1600gp 12 R&R points
1 Year 600gp/1200gp/2400gp 18 R&R points
This allows players to take breaks when the opportunity is there, but still rack up the levels (and extended rest) when needed.
Of course, what the OP is actually getting at is something else...