Good quality 1/4" line will last at least 10 years.
What brand and where do you buy it at? What type also is it?
I have used that clear vinyl stuff you get from Ace Hardware. It lasted like 5+ years until I sold that push mower. It is not even fuel rated that I can tell. Just the cheap clear non reinforced stuff.
I know the stuff from Autozone and O-really's is junk. I've bought their fuel injection hose as well. Still get about a year or so till it gets hard and starts leaking. They only sell Gates if I recall correctly. That was when I used to drain all my equipment for the winter. Obviously it leaves the lines dry to well, dry out over the winter. All my mowers are in the garage. Better than outside.
Started using Stabil year round, leaving fuel in the machines. No more issues with dried cracked lines. Got a 9 year old Maruyama trimmer with the original lines on her.