If I'm drinking a blended whisky, I put ice untill the top of the glass, except for some special ones (12 years old or more).

For single malts, and those specials, I add just an ice cube on summers (it can be easily over 35ºC in August over here) or any in winters. I never added water apart of that of the icecube,... and i let it melt for some seconds before starting to enjoy it!.

Just as a curiosity, in Spain we use to say that there is an scottish said that states that:

"The first whisky,.... with water,
the second,.... without water,
...and the third....like water!" ;-)

¡Salud!

T O N O