Although everyone has their own opinion, the opinion of someone who's opinion I trust is that a 23 litre carboy is not large enough to provide the benefits of bulk aging. Therefore it doesn't matter whether you age in carboy or bottle. Personally I usually do a combination of the two. I drink very little red wine that is less than 6 months old, and most is definitely older.
How much aging a wine requires depends on the wine and your tastes.
You want to be bottling a wine that won't continue to set sediment (ie it is clear) or continue to ferment in the bottle (ie it is stable).
There are two meanings for secondary fermentation. One is a second fermentation (ie Malolactic Fermentation or MLF). I do not know when it is safe to bottle after MLF.
The second meaning is really the completion of the primary fermentation. In the kit world, the primary ferment usually runs 7-10 days and refers to the vigourous ferment (down to say sg 1.000). The main fermentation continues in a secondary fermenter or carboy until the wine is dry (generally sg below .995).
In the kit world, K-meta, sorbate, & clearing are now added. Along with vigourous stirring (and possibly vacuum) to degas the wine. After a further period of time (varies depending on instructions & winemaker), it is now safe to bottle.
At this point the wine has been cleared by finngs agents, gravity, successive rackings, and/or filtering. The wine is stable because ALL fermentation is complete, and the yeast has been stopped by the K-meta/sorbate combo.
I answered NO this afternoon because I thought you were suggesting bottling before the stabilizing/clearing steps. In reality, I should have asked what you meant by secondary fermentation being complete.