How often to apply wax,to cabinet?

I had read that a good wax,like Briwax/Sheradale is the best care for speaker cabinets,with a laquer finish.I applied a good coating one year ago,and have my speakers in a dedicated room,with no smoke,and little dust.
How soon do I need to reapply the wax,as it is "work" to do correctly.I do not notice any wax loss,but want to keep the surface perfect.
Thanks in advance!