In short, you grab a datasheet for the tube (6AN5) and look at the pin diagram. And then you compare the pinout to the EF1, EF92 and EF95. If the pinout is the same, you can simply plug it in, as appropriate. In the case of the 6AN5, you can see that the Beam Plates/Grid 3 and the Cathode are strapped together inside the tube. And if you compare this to the EF95 pinout, you will see the identical pattern. Therefore, I can see no reason why this tube wouldn't work in the EF95 setting.
And this is the reason we strap pins in the socket: To make the tube pinout appear to be an EF91, EF92 or EF95 so that we can then use them in the LD.