Discussion Tipping by Percentage: Does It Still Make Sense?

I’ve been thinking a lot about tipping culture, especially when it comes to dining out. Scenario: Diner #1 orders a $50 entree and a $10 dessert, while Diner #2 orders a $20 entree and a $5 dessert. Both receive the same level of service. Does it really make sense to tip based on a percentage of the bill, or should we consider a flat rate for service quality? I’m curious how others approach this, especially in different countries where tipping norms vary.