Hex recess individual sockets rather than multi-spline because it supports the side of old bolts a lot better, so much less prone to rounding off.
Yes, you can often find a metric one in your toolbox that is close, but you run the risk of rounding off those old bolts when for a few quid you can get the correct imperial one.
Good standard quality Imperial sockets sold individually so you can replace any in your set that are worn out or broken - or to expand your range.
Chrome vanadium steel hex. Chamfered end for positive nut location. Radius design for added torque and long life. Knurled band, ball-retention hole. To DIN3124/ISO2725 and DIN3120/ISO1174.
Item shown is an example from the range but obviously they vary to suit the different sizes!