Maximizing gameplay time in Spiral Knights

Solution 1:

While, generally speaking, you are limited to ten floors of a dungeon per day, each dungeon is split into 3 separate Tiers. Each of these tiers starts at a different depth - 0, 8, and 18, So if you have Tier 2 Clearance, you can start at floor 8, and go all the way to floor 20 (no energy costs to access floors 13 and 18).

Likewise, if you start at floor 18 (tier 3 clearance), you can make it all the way to the core, Level 29, and still have 10 energy left over.

The one downside of this is that starting at Tier 2 or 3 costs Crowns (the in-game currency) -- 200 or 500 respectively. However, if you work your way through one gate sequentially - getting to floor 8 the first day, getting to floor 18 on the next, etc. you will avoid having to pay the cost in crowns.

Since gates have an 8-day cycle, this means you will be able to delve all the way to the Core 6 out of 8 days, avoiding the 'tax' for jumping directly into the deeper tiers. Alternatively, just jump directly into Tier 2 and Tier 3 without clearance; the Crown tax isn't that bad, and you will generally recoup your entry fee within the first floor or two.

Solution 2:

As of the July 30, 2013 update, mist energy has been completely removed, and there is no energy cost to use elevators.

Thus, there really is no "ten floor maximum" restrictions now. You can explore the Clockworks to your heart's content!

Solution 3:

I think the idea is that you have to be generating enough crowns to buy crystal energy. This may require you to make several runs with just your free energy for each run that you do using crystal energy (depending on the current market prices and how many crowns you can accumulate per run), and limiting your other crown expenditures as much as possible. When you do use your crystal energy, it is especially important that you do so in a way that nets you a bunch of crowns, to get you started towards your next crystal energy purchase.