Generally I use OpenPGP V2.2 or OpenPGP V3.3 smart cards in different roles and one Yubikey. For best practice the key is always generated straight on the card. Five of my cards worked fine, but one card failed (OpenPGP V3.3). It took a while, until the message "Key generation failed: Card error" showed-up. I contacted the vendor, because I bleieved that the card was dead at arrival.
However, the vendor told me that it is a common problem. The time for key generation would be too long and therefore a time out would happen often. They recommended to generate the key on a computer and copy it to the OpenPGP card. Definitely no best practice. I have not yet tried this work around. I´ll check it out next weekend. However, I would like to bring the issue to your attention.