“More thickness = more speed”
The formula circulates with the authority of things that seem obvious: if a thicker sponge has more material to deform, it will store more energy and return the ball faster. The logical conclusion would be that maximum thickness is always the fastest option, and therefore the best for anyone wanting more speed. The premise is partly correct. The conclusion is not.
What thickness does is amplify the energy the player supplies, not create it. Section 5.7 develops the physics: more sponge allows greater deformation, lengthens the contact time and makes the catapult effect easier to activate (2.4). All of that is real, but it only shows up when the stroke carries enough force to compress that sponge into the zone where restitution turns non-linear. The threshold exists, and it depends not on the thickness but on arm speed and cleanliness of contact. Whoever does not reach it does not get the promised speed: they get a sponge that absorbs energy without returning it proportionally, a ball that leaves with less control and, often, with less speed than a thinner sponge would produce off the same stroke.
The myth survives because it holds for the player who does have the arm speed. A trained attacker moving from 2.0 mm to maximum thickness notices a real jump in speed, because the stroke compresses the sponge into the productive zone and the additional material works in their favour. That player recounts the experience, posts it on a forum or in a video, and the club player with half the arm speed takes it as a general rule. The problem is that the rule describes a particular case, not a universal law. Thickness multiplies; if the factor being multiplied is small, so is the product.
There is a second aspect the simplification ignores: what is lost in gaining thickness. Every tenth of a millimetre added to the sponge moves the ball further from the blade. The player feels the structure of the bat less, the touch becomes more diffuse, and the short strokes —receives, flicks, blocks over the table— lose precision because the sponge filters more than the stroke needs at those moments. Section 5.7 notes that the weight difference between 1.8 mm and maximum thickness can exceed five grams per side, which adds more than ten grams to the assembled whole. In a game decided in milliseconds of reaction, the extra weight is not free.
The third element the myth omits is the interaction with hardness. A thick, soft sponge amplifies a great deal but feels imprecise on fast strokes; a thick, hard sponge is the most demanding combination in the catalogue, reserved for the player with high arm speed and proven technical consistency. Thickness is not chosen in isolation: it always operates alongside hardness, and together they determine the character of the rubber (5.6, 5.7). Choosing maximum thickness without considering the hardness of the sponge mounted means making half a decision and leaving the other half to chance.
What remains once the formula is dismantled is a more useful criterion: the right thickness is not the maximum available but the one the player can activate with their habitual stroke, not with their best one. A 2.0 mm sponge working in its optimal zone on eight contacts out of ten produces more effective speed than a maximum-thickness one that only activates on three. The criteria for that choice are developed in 7.2, and the bat profiles in chapter 12 incorporate thickness as part of the combination rather than as a loose variable. Real speed does not come from the thickness: it comes from the stroke. Thickness only decides how much of that stroke is put to use.