I know some personally and they are in the gym 2-3 times a week. It’s an important factor for them as they have to remain injury free but they aren’t bulking that’s for sure.
when i was training for the ironman i absolutely did weight training, but only 2-3X per week and for 30 minutes max.. did it help me on race day? absolutely. you need to have a lot of strength, stamina and willpower to get out of your swim into your next event and muscle speed and mass