i have Ladder Spikes fitted ,these are an absolute godsend if the ground is damp as i can place the spikes into the tiniest of crack and no chance of my ladder slipping away.
Worst safety idea i ever bought was LADDERMAT. they are rubber mats,sold stating they are very good on smooth or slippy surfaces. i trusted them ,one day mine slid 10 feet on a Quarry tile path and i fell the full drop,damn lucky i didnt break both legs or worse

i posted on this forum about it and several replied saying theirs too slipped ,i even contacted the maker but he brushed me off -a total charlatan - dont buy Laddermat if you value you or your staffs lives