I wear it not too tight and not too loose. Cos if the weather is cold, the watch will be a little loosed at the size you chose. Vice versus, the bracelet will be a little tighter when the weather is hot.

You might want to know why the bracelet "shrinks" in hotter weather and "expands" in colder weather. The answer is NO, colder climate the bracelet logically contracts and hotter climate the bracelet expands a little. However, this phenomenon also applies to our wrists. Our wrists shrink more than the bracelet in colder climate and expand more than the bracelet during hotter weather.

The above is based on what I personally experienced. Hence I would size it just not to loose or too tight.