As someone who started doing web development in 2003-2004, I've always aimed for a 5 year support window. This is largely because of how long IE6-IE8 upgrades took for many SMB's and governments to upgrade from in those days.
Back then browsers updated closer to 2-4 times a year, with far lower inertia in how drastic the changes would be. You could learn and mostly remember what features were safe for roughly that period. These days, I tend to look at feature release dates and support on CanIUse or MDN, to see if somethings been in broad use for the past 4-5 years.
Back then browsers updated closer to 2-4 times a year, with far lower inertia in how drastic the changes would be. You could learn and mostly remember what features were safe for roughly that period. These days, I tend to look at feature release dates and support on CanIUse or MDN, to see if somethings been in broad use for the past 4-5 years.