For players who play strictly basic strategy, the depth of the cut card has no effect on their advantage. For anyone who is not counting cards, it is never a good idea to make an insurance bet. Many people automatically make an insurance bet if they have a blackjack or perhaps other very good hands. Many counting systems have a specific true count value that would indicate when it is beneficial to make an insurance bet. There are almost as many betting strategies as there are gamblers.
Many people have complex betting patterns based on the results of their previous hands.
In order for a betting strategy to be effective, you must know when the cards become favorable for the players. There are numerous counting strategies that can do this. You get more of a benefit from altering your playing strategy based on the true count for single and double deck games than you would for 4 or more deck games. It is best not to give advice to other players who you do not know. If they end up losing the hand after taking your advice they probably will hold some animosity towards you and will let you know it.