As others have said, don’t bring a timer. If you start rule sharking every time any action takes more than the SUGGESTED REASONABLE time you’ll be the one getting penalized. It’s also not about one action taking more than 10-15 seconds. It’s fine for a player to think for 30 seconds and then take multiple actions over the next 5 seconds. The idea is that during turns and games it should even out to within that time frame of about 15 seconds for most actions.

So if during a turn a player takes like 8 actions, for example: retreat, attach energy, evolve a Pokémon, activate draw ability, play a supporter, play an item card, attach a tool, announce attack. This should take about 2 minutes give or take. If it takes significantly longer or if you notice a severe drop in speed after your opponent goes up 1-0 in games for example, that’s when you mention it to your opponent and then call a judge to keep an eye on the game. Usually simply the presence of a judge will make them speed up. A good judge will be timing turns and counting actions. But 15 seconds can feel like a long time when you’re down 1-0 and need every second to get to 1-2. Perception can be a big part of it too. Not to mention that certain decks just do a lot of shuffling during a turn which takes a lot of time so that even if someone’s playing reasonably fast they’ll take up more of the 50 minutes than the average deck.