Split-Pushing 101

Short and simple: the goal of split-pusher is finding the balance between pressuring the map and surviving.

• You don't provide map pressure if you're dead.
• You will die, as a split-pusher, if your Top Lane counterpart from the enemy team is able to kill you by his/herself.
• You will also die, as a split-pusher, if it is efficient for the enemy team to kill you.
• It becomes efficient for the enemy team to send multiple people to kill you if your team isn't visibly pressuring another area of the map (i.e. Neutral Objectives or Turrets).
• You don't provide map pressure if your team is dead.
• Your team will, most likely, die if your Top Lane counterpart participates in a team fight and you do not. This is known as a numbers advantage.
• A numbers advantage exists when it is statistically suggested that an advantage is gained by another party based on the number of individuals in said party in comparison to the second party.
• Map pressure (and by extension, split-pushing) is made useless when you fail utilize the advantage gained through good decision making - the internal debate most often being enemy structures vs. fights.
• If you decide to take enemy structures, you need to have assessed whether or not your team can continue to hold the enemy team at bay at a numbers disadvantage.
• If you decide to fight, you need to have assessed your potential impact in said fight or whether it's actually viable to fight at all.