Because it bears against a much larger area of the back of the board.

Every hollow-wall fixing ultimately loads the board itself. Capacity is decided by how much board area is carrying that load before it crushes or tears.

A toggle wing spans well beyond the hole, so the pressure at any point is low compared with a sleeve or a threaded anchor bearing close to the hole edge.

That advantage grows with load. At light loads all types work; at heavy loads the difference between them is the bearing area.

It is still the board that fails, not the toggle, which is why a spreader plate or large washer on the face extends capacity further.

Fixing into a stud, where one is available, is stronger than any hollow-wall anchor including a toggle.

On a classic spring toggle, the wings drop into the cavity and the fixing is gone. On a strap or snap-off toggle, the anchor stays put.

Spring toggles hold the wings only through the bolt. Unscrewing it releases them, and they cannot be retrieved.

That leaves an oversized hole - larger than the bolt because the wings had to pass through it - which usually needs a new fixing position or a repair.

Strap toggles solve this by holding a metal channel flat against the back of the board with a plastic strap, then snapping the strap flush.

The result is a captive nut behind the board that can be unbolted and rebolted repeatedly.

For anything that will be taken down and refitted, that is the deciding difference.

Enough for the wings to open fully - and a shallow void, insulation or a service behind the board will stop them.

A wing that opens only partly bears on a fraction of the intended area, and the fixing feels tight while holding very little.

The required clearance is stated by the manufacturer and grows with toggle size, so the largest toggles need the deepest cavities.

Insulation packed tight against the board is a common and invisible obstruction.

Pipes and cables behind the board are a safety problem as well as an obstruction, and are worth checking for before drilling.

Where the cavity is shallow, a threaded or self-drilling anchor that stays within the board is the more appropriate choice.

Larger than the bolt - big enough for the folded wings to pass through, which is stated on the packaging.

This is the toggle's main practical cost. The hole is oversized relative to the fastener, and it is visible if the fixture does not cover it.

Drilling smaller than stated and forcing the toggle damages the board around the hole, which is exactly the material the fixing depends on.

Drilling larger reduces the board area available to carry the load and makes it harder to keep the toggle in position while tightening.

A clean hole matters. Ragged edges from a blunt bit reduce the bearing area on the face side.

Because the hole is large, repositioning a toggle a short distance away is often not possible - the two holes merge.

They work in both, but old plaster is a much less predictable base and needs care.

Traditional lath and plaster is brittle and often loose from its lath, so drilling can crack a wide area around the hole.

Drilling slowly, without hammer action, and from a masonry bit rather than a wood bit reduces cracking considerably.

Where the plaster is sound and reasonably thick, a toggle bearing on the back of the lath performs well.

Where it is friable, no hollow-wall anchor will be dependable, and fixing into the structure behind is the only reliable answer.

Because condition varies so much within one wall, testing the actual fixing is worth more than any published figure.

Pull the bolt towards you to hold the wings against the board, then tighten steadily and stop when the fixture is firm.

If the toggle is not held back, it spins with the bolt and never seats against the board.

Over-tightening is the common failure. The wing pulls into the back face and crushes the board core, after which the fixing loosens permanently.

Power tools make this easy to do and hard to feel, so the last part of the tightening is better done by hand.

A washer or the fixture's own flange should cover the hole so the head does not pull through the face.

If the assembly turns without tightening, the wing has not opened and the fixing has to be removed and repositioned.

Substantial shear loads along the wall, and much more modest loads pulling straight out - and never a safety-critical one.

Shear is the favourable direction: the board is loaded in its own plane and the wing resists rotation.

Direct tension crushes the board around the wing, and that is what limits published capacities in plasterboard.

Most real fixings combine both, and a shelf or cabinet applies a turning moment that converts into tension at the top fixings.

Spreading load over more fixings, and using a spreader plate or continuous batten, does more than upgrading the anchor.

Anything overhead, structural, or where failure would injure someone should be fixed to the structure behind the board.