Yup, I do have a dishwasher. About 5 years old now. Specifically renovated the kitchen to fit a dishwasher before moving in. Brand is Teka and never had any problems with it.

As to why. Question should also be why not? Do you do your laundry by hand or do you have a washing machine? Same reason - saves time by just have to load everything in and the dishes will come out clean and dry.

Depends on the mode. There are quite a few to choose from.
If use eco mode between 2.5 to 3 hours.
If use normal mode then is 90min
And if want quick wash there is 30min as well.

Its a full size dishwasher, so can wash a full set of 16 place settings or can put in pots and pans also (most not be non-stick of course).
In Eco mode, it uses 0.91kwh.

If you have lunch at around 12pm to 1pm and dinner at 6pm or 7pm, there is already 5+ hours for the dishwasher to complete the most water and energy efficient wash and dry cycle before the next meal. Or are you having second lunch or dinner?

But since you asked, the 30 minute cycle is even lower power consumption at 0.6kwh - mostly because this is only a wash cycle without drying.
The quickest cycle with drying is the 90 minute cycle. Power consumption increases to 1.35kwh.