If its the 15-20 minutes it takes to do it once or twice a month, than I can't help you

Mind you I have been doing partial water changes in Fresh and Marine Aquariums for over 30 years now. And that would equate to thousands of water changes!
So here it is the K.I.S.S. approach to h2o change.
Gather up the tools for the job:
*Grab a couple of your designated water change buckets (you know the one you don't use to mop the floor or wash the car), the clean ones , virgin to all soaps.
* Grab your gravel cleaner/ siphon
* Your water conditioner / chlorine remover
* Your glass cleaning sponge or magnet
* A towel
* replacement filter cart. / airstones etc.
I figure that should have taken you about 3 min., unless your a beer drinker and that may have been good for 12 oz's.
now the general rule of thumb is a "MINimum" of 25 % once a month, I express this because its not set in stone, different feeding habits or fish stock will play a role in amount and frequency. For the sake of this ex. well say its the common 30 gallon tank. So thats about 10gallons we will remove.
1st thing, lets go ahead and fill 2 buckets (approx 10 gal) with fresh water or mix salt water if it a marine aquarium, add the dechlor and add a little hot water to get temp within a few degrees of the main tank.
With that done go ahead and pull out 2 buckets of water using your gravel cleaner. So to make a quick recap........you've premixed your water in advance of draining, and you mixed up exactly what you are going to remove....SIMPLE huh.
With the 25% water removed, this is when I get the sponge out and clean the glass. Change the filter cart. if you have any, etc.
once thats taken care of, either pour the water back into the tank via the buckets themselves or pitcher it back in, a little at the time.
Thats it, your done!
Now comes the little things.....if its a Saltwater change, try and mixed the salt the night before, use a powerhead or air pump to keep the salt circulating. This will give you the time to insure the salt level is the same as the main tank, by adding salt or freshwater to the bucket.
Remember all you want to do is have the prepared water as close to the same properties as the tank water, ie. temp / salinity / ph etc., but without the poop.