Our best free-kick taker takes every single one

I would deliberately develop at least one or two alternatives. Your best taker can still take the important free kicks, but if nobody else ever gets meaningful match reps, you create a dependency. Use different zones or game states to share responsibility. One player might take wide free kicks, another corners from one side, while your strongest taker keeps the most dangerous central situations. You can also rotate during periods where the score or competition context allows it. At U17, players are close enough to senior football that having several set-piece options is valuable. The second taker needs genuine pressure reps, not only ten deliveries after training. I would explain the plan to the best player so it does not feel like punishment for being good. You are not reducing their value. You are building squad depth around a specialist skill and protecting the team if that player is absent, marked, injured or simply having an off day.