1 year warranty on window installation labor?
Look at it this way - they are setting the prices and giving the work over to a lowball sub-contractor who is just starting out in business or he wouldn't accept their price scedule. Then he has to work like a madman to install enough windows in a day to make a living at it.
HD messes up his schedule occasionally so he ends up in a bad mood some days.
and then you want HD sending him to work on your home???????
Anytime you hire based on lowest price, you can count on a strong chance of getting the lowest quality. Therefore they need to offer a warrantee to build customer confidence.
You will know if anything is wrong with the installation after the first couple of storms. A year is plenty long enough for any installation problems to crop up.
You will want a copy of the contractors liability insurance before letting them on the property tho. If something else is damaged or destroyed in the process, you'll need the protetion.
Specified "otherwise" can mean NO warranty on labor and materials.
Home Depot is no more or no less better for providing warranty on replacement windows than anyone else.
1 year is 'normal' in most applications but can be more or less depending upon specifics.