Assuming we're talking metal machine tables, use metalguard every 6-12 months as protection from rust and once dry, liberon ((liquid, machine table) wax on top, renewed as needed.
I used Kity Speed which was just repackaged Silbergleit table wax and it was fine on Kity's alloy tables, but the 2 part approach above is better for cast iron.
In every professional workshop I know, the first job every morning is to wipe down every machine table with Woodslide, Waxilit, Silber Gleit, Liberon Lubo, Axminster Machine Wax or some other silicon-free machine table lubricant.
And if they're a joinery workshop, using lots of resinous timber, then they might repeat the process every lunch time!
As has been pointed out, a tin of the proper stuff will last a lifetime and it really does make a huge difference. No risk of fish-eye on your finishing and safer too as it reduces the amount you have to push on the workpiece.
Interesting - I work with my brother on occasions who has been a professional for 35 years, and when asked about this in the past he avoids such lubricant like the plague arguing that the friction helps to prevent the wood going through the machine too fast giving thereby giving a cleaner finish and less hazard of lost fingers / planed of fimger tips.