Not a good idea if you want to get a guaranteed place to sleep. It's not that easy during holiday seasons and weekends. Because hiking is booming. You can book by phone or online on the hut websites. The latter show if a place still has available beds. So the hut tenant doesn't have to answer the phone a hundred times to say "fully booked". You can also find out on the web when the Ötztal huts are open at all - usually from June/July to mid/end September. Short-term changes are possible, for example due to bad weather towards the end of the season.
Unfortunately, you can't come? Then please cancel reliably. This means that someone else can make a booking, the hut keeper can adjust his shopping list and the mountain rescue team doesn't have to look for people who did not show up at the hut.
By the way: if you want to take your dog with you, please ask the hut tenant already in advance whether this is possible.