Downtime is Good

[SirNibbles]

Downtime, or the time that passes in game while the players are not at the table, is a very important aspect of D&D. If used correctly, it helps avoid unnecessary slowdowns, allows for long-term planning, and helps increase immersion and verisimilitude. Conversely, a lack of downtime leads to a feeling of major events being rushed, pointless encounters soaking up session time, and a lack of immersion.

Part I - Shopping
In a game with a lack of downtime, players shop for items while they're at the table. This takes up time and completely breaks immersion for the rest of the players who aren't interested in what junk the other players are buying. Unless you're playing Merchants and Wagons, haggling over every item is just an annoyance. If the prices are static, there's no real need for everyone's time to be consumed by buying things. Just tell the DM between sessions what you want and if it's not available at your current location he will tell you.

Part II - Levelling
What do level and XP represent? They represents how good you are at a thing and how much time you have spent doing a thing, respectively. You get better at something by practising it. This is represented by your XP gains. When you gain enough XP, you are better at that thing that you have practised, and so you gain a level (and perhaps a feat and ability score bonus). A wizard studies books on magic to get better and applies his studies when he casts spells. A fighter reads treatises and manuals on combat, lifts for mad gains, and practises his weapon techniques. A monk meditates, practises his forms/strikes, and studies martial techniques from scrolls and books.

If you don't have (enough) downtime, you end up gaining levels without there being any time in which you could have done this training. It breaks immersion a bit. This is especially true if you are multiclassing or entering a prestige class. Are you saying that the experience you got as a Monk by punching things until they died somehow allowed you to learn Wizard spells? That's what would happen without downtime. With downtime, we know that the Monk simply trained as a Wizard during his downtime while doing more monk-like things during the actual session.

Part III - Crafting and Other Skills
Crafting is nice. It allows you to make custom items. You simply can't do it without downtime. It's also nice to be able to make money by crafting goods, performing, etc.

Part IV - Family Life
Having a family is a great way to make you empathise more with your character. Downtime allows you to do that without interfering with the gameplay experiences of the other players. Again, the setting becomes more believable when you have a family with which you can interact, especially for extended periods of time.

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The amount of downtime a character has between sessions may vary from session to session (including having none at all between some sessions), but I think it's important to have at least some downtime over the course of a campaign, including extended downtime (at least a week).

[Beheld]

I think you have the wrong definition and the right idea. Downtime for the characters is not always best represented when not playing. People should have more downtime during games to all the things that it makes sense for a character to do and to be able to do those things with their character while playing.

[Mendicant]

Downtime for the characters is not always best represented when not playing.

Not always, but usually. Character appropriate downtime tends to be very individual, and a table with one DM just doesn't run well with everyone trying to play out their specific weekends and holidays.

When I was in high school I had a lot more opportunity to do one-on-one stuff that allowed for in-person downtime. Now I keep that as much as possible to a loose minigame done online.

[Zanos]

Fun fact, a 4 man party doing the standard 4 CR = Party Level encounters per day is level 20 at the end of the 64th day. Or just a little over 2 months.

(13.3333 * 19)/4 = 63.175
13.333 Party level = CR encounters per level.
19 level increases
4 encounters per day.

So agree with the general idea that downtime is important for versmillitude. It's not uncommon for adventurers to at my tables to take multiple months worth of downtime between big adventures to get their affairs together, especially at higher levels when they have lands to rule and big items to commission.

[Kelb_Panthera]

Couple things:

1) You've conflated player downtime and character downtime. They often don't coincide.

2) Character downtime is a tool like any other narrative tool. Whether it's good or bad is more in how you make use of it than in the concept itself.

3) When character and player downtime do coincide, you're absolutely right that it's a great opportunity to deal with game mechanics that don't directly contribute much to the narrative or group enjoyment during a session, i.e. shopping, crafting, dealing with non-cohort followers actions, etc.