What’s the one air-sensitive or Schlenk technique that gives you instant anxiety when reading a procedure?

Just watched a tiny pinhole leak in a cannula transfer kill an entire afternoon of work, and I need to vent before I go reset the Schlenk line.

Doing organometallic or moisture-sensitive chemistry is a completely different level of paranoia. The paper will casually say "all manipulations were carried out under an atmosphere of dry argon," but they completely skip over the two hours of flame-drying glassware, degassing solvents, and praying your septa don't degrade mid-transfer.

My personal list of inert-atmosphere misery:

1. The Cannula Clog: Pushing a fine slurry through a double-ended needle under positive pressure, watching the flow slow down to a crawl, and knowing a single rogue grain of solid just jammed the needle halfway through the transfer.
2. Glovebox Static: Trying to weigh out 5 mg of a fluffy, air-sensitive catalyst inside a drybox while static electricity makes the powder literally levitate off the weigh paper and stick to the plexiglass walls.
3. Grignard Initiation Panic: Staring at magnesium turnings in THF, dropping in a crystal of iodine, applying gentle heat, and wondering if it’s actually initiating or if you're about to trigger a massive runaway exotherm the second you step away to get a coffee.
4. The "Dry" Solvent Betrayal: Trusting the lab solvent purification system (SPS), only to find out the alumina column died three weeks ago and your reaction just got instantly quenched by 500 ppm of water.

Whenever I see "filtered through a medium-frit Schlenk funnel" in a paper's supporting info, I know someone spent three hours fighting a clogged frit under positive N2 pressure.

What’s the one air-sensitive maneuver or Schlenk setup that instantly makes you dread setting up a reaction?