Every joint — the mortise and tenon, the dovetail, the dado, the drawbore — has one moment where it can still go wrong. Not when you're laying it out. Not when you're cutting it. Not even during the dry-fit.
The moment the glue comes out.
You have a short clock. PVA (yellow glue) gives you 5–10 minutes of open time under normal shop conditions — shorter in a warm, dry shop, shorter still on porous end grain. Hide glue buys you 15–20 minutes and has the advantage of being reversible with heat and moisture, which is why it's the traditional choice for chairs. When that seat rung needs to come out in thirty years, hide glue cooperates. PVA doesn't.
Know which adhesive you're using before you open it. That's not a preparation step. That's the job.
Stage first. Always.
The rule everything follows from: set up completely before the glue comes out.
Every clamp pre-set to approximate length. Cauls cut and sitting where they'll be used. A square and tape measure within arm's reach. Rags or a bowl of water ready for cleanup. If the assembly needs a second pair of hands, those hands are in the shop.
The dry-fit told you the joint closes. It didn't tell you what happens when adhesive lubricates the surfaces and the closing slows, and then the glue starts to grab at an inconvenient moment. What it didn't tell you is what it's like to be three clamps in with a fourth one across the room.
Walking to find a clamp after the glue is spread is how you end up clamped out of square.
How much pressure
Less than you think.
The goal is to seat the shoulders and keep things in alignment. It is not to compress the wood fibers, force out every bit of adhesive, or wrestle a bad fit into submission. A joint that needs heavy clamping pressure to close is telling you something. The tenon is too thick. The shoulders aren't seating. Glue won't fix it, and heavy pressure will only manufacture a stressed assembly that comes back to haunt you later.
The diagnostic is squeeze-out. A thin, even bead at every shoulder line means good coverage and correct pressure. No squeeze-out means not enough glue or not enough pressure. Heavy, foamy squeeze-out means too much of both.
Aim for the thin bead. It's not hard once you know what you're looking for.
Check after clamping, not before
Clamps introduce forces. Those forces change geometry. The assembly that measured square before clamping may not be square after.
Two checks: diagonal measurements corner to corner (equal diagonals mean square corners), and a straightedge or winding sticks across the top to confirm nothing has twisted. Both checks need to happen while the glue is still open — while you can still do something about it.
If the assembly is racking, remove the clamp that's causing it, add a strap clamp across the long diagonal, and re-measure. Most assemblies come back in the first few minutes if you catch it immediately. After the glue starts to cure, that window closes.
The squeeze-out problem
Don't wipe it. Not yet.
Wiping wet PVA spreads it into the surrounding grain and creates a finish trap — oil and stain won't absorb evenly over glue-contaminated wood. Wait until the squeeze-out gels to a rubbery consistency, which takes 30–60 minutes. Then pare it away with a chisel. Clean and done.
Hide glue is water-soluble when wet and can be wiped with a damp rag in the open time. On porous species, a quick wipe is fine. The moisture won't cause the surface problems that diluted PVA does.
For fine work on visible corners, apply glue only to the tenon cheeks and mortise walls — not the tenon end, not the mortise floor. Less squeeze-out at the shoulder lines where it shows.
The glue-up fails before the glue comes out. It fails in the staging, in the missing clamp, in the square that wasn't in reach. Everything after that is consequence.
Set up completely. Move with intention. Check square after clamping. Leave the squeeze-out alone until it gels.
The joint doesn't know you're in a hurry. The clock does.