For Type 1 Fixes, ‘Buttonfix strength testing report’ is available here.
The figures in the table are for four Type 1 Fixes (in a standard ‘2 x 2’ array) and are already adjusted to give a 1.4 safety factor. These figures are actually the maximum for two Fixes only; this is because theoretically, allowing for inaccurate fixing of the components, only two Fixes can be guaranteed to be loaded at one time: this applies to any size of panel, with more than 4 Fixes.
In practice, with reasonably accurate fixing, and with their inherent flexibility, the load will be shared between most of the components, and the safe loads will increase with an increase in the number of Fixes used.
As can be seen from the design tables, It is a good rule of thumb to aim to keep the ‘cantilever’ distance — that is the ‘shelf depth’ — shorter than the height between the Fixes.