The pressure settings recommended for fuel gases will vary somewhat between manufacturers depending on tip sizes. There is no standard between manufacturers on tip sizing. Fuel gas flow through the tip is determined by pressure settings at the regulator. Sufficient pressure is required to cause sufficient gas flow through the tip, to keep it cool during operation. A correctly set flame may appear to touch the tip but actually there is a very small gap between the base of the flame and the end of the tip, but it is not possible to see without magnification.
Insufficient flow causes the flame to actually touch the copper tip end and builds up heat.
With Smith Equipment welding tips, the charts show 10 psi for fuel gas. It is acceptable to use a lower pressure. These charts use the assumption that safety devices may be in the system, which cause some flow restriction. Unless you are working with very small single flame tips, I suggest you use a minimum of 5 psi, each gas.