It depends entirely on their position. If it is windy and exposed and you want a straight tree, you need to stake them.
We get a lot of swirling winds and bent plants in a very sheltered garden. Unless you are certain you don't, stake it. A stake and strap is cheaper than your tree.
swirly winds, exposed, 4-5 fooyt trees - stake until established I reckon! 45 degree stake against prevailing wind.....
But from personal experience, to avoid bark damage and subsequent canker problems, use a soft wrap between the stake/tie/tree
What it really depends on is the rootstock. Some rootstocks have to be staked forever; some can dispense with a stake after some years. Look on the RHS site.
Funnily enough it isn't the prevailing wind that does the damage. Trees do get used to the normal direction. But if a gale comes from a different quarter - that does the damage. But, yes, if in doubt, stake and replace the stake if it rots.