OT, I adore my 28 sellier kelly (DH says it’s the sexiest bag in the world lol) but it is most convenient to do up both straps under the flap, so you just have to twist the turnlock and lift the flap to get in. Caveat is, I can get my hand inside and lift out smaller things, without undue stress (On the bag). For fastest access (like in a grocery store line) I do carry my Amex in my cargo pants pocket. But, For a retourne, especially a larger size (this one may be a 32?) I think it should be even easierto slip on ones hand in to pull out a phone or wallet. This presumes Of course your hand can easily fit and doesn’t stretch or strain (the bag)

of course, YMMV.
@Pinkie, Your pic is gorgeous, but some people even carry the bag without doing up the turnlock. As per
@duna, your way, If your bag is loaded, over time, the turnlock could bend. As
@periogirl28 advised, if you even do up one strap it would provide a little more support. BTW, I have owned a preloved bag at one point whose turnlock was slightly bent (By previous owner) and I was careful with it. IMO bent turnlock Isn’t good, but is far better than Damaged spine or Loose base lock or shoulder pad. Note: a beater kelly can be very chic, but hopefully one gets it at a beater price. and, IMO, if you want to load an unstrapped bag with heavy stuff, wear a birkin. Below, two pics of kelly bags strapped under the flap.
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