Both have their benefit, the can is the most economic way to apply it

I sometimes remove the dish reflector and take it into the garage or some other well ventilated area and spray it there. Let it dry then re-bolt the reflector to the dish mount, making sure not to touch the treated area.
Of course its a complete WASTE of time and money using the spray on a windy day. That's whats nice about the wipe, its dripping wet and really coats the surface very thickly. It can be applied in the wind but all other recommendations must be carried out to get the most and longest out of the product!
I would recommend using the wipe mainly on the dish making sure to get the whole surface area soaked, just when its starting to dry out a little I wipe the top half of the rim of the dish then any snow that does manage to land there will be instantly blown away.
I would then wipe the LNB cover and the top half of the LNB casing, and finally wipe down the LNB arm with any remnant product!
Have any spare LNB's handy so that you can give them a wipe down while you are at it!
Should last a year, I had been applying the spray twice a year, once in fall on the last warm day, then in spring on the first warm day.