Simple answer is, I don't. I manage huge populations.
My Fortress is predominantly surface-level construction to facilitate farming and fuel harvest. The mines and the quarries will be built into as required, but there has been no such need, aside from the jail and the dungeon (a dumping ground for trapped thieves). I prioritize defense, and as such have only just suffered my first casualties, 5 years in, at 1M fortress value.
Industries are being established as rapidly as it is safe to do so. At present, 1/3 of my fortress are assigned general labour duties which include construction, butchery, tanning, plant processing and other unskilled tasks. Things tend to get done as fast as I get around to designating tasks.
Idlers wax and wane with the tides and the trades. Having yet to complete my castle, invaders tend to disrupt my less-skilled industries, found closer to the frontier gates.
We are running a tetra mine. Our ores are converted to billon at a profit, but as we have yet to attract a metalcrafter of quality, most of our worth is on account of the thriving clothing industry and one very clever jeweller. There have also been dramatic fuel shortages in recent years, though this has not prevented us from using billon as our standard furnishing material.
Ever since the flood, the miners have been sitting on their heels, waiting for the smelters to catch up before commencing a new project incorporating underground farms, sewers, and liquid defenses. We were very lucky that it had occurred in a distant branch of the mines, isolated by ramps.
My only gripe is that with the extra social time, my broker has been replaced as mayor by some upstart with a penchant for nickel silver...