I'm practicing my Tanking skills constantly. And, some FATES do provide prime Tanking training. Svara in Coerthas is a great example of training holding aggro, positioning the enemy so their AoE doesn't hit the others, dodging AoE, timing mitigation CDs, et cetera.

The A-1 problem I have is, as has been said, people who run out ahead of me (I am a VERY deliberate player and I don't run...); and the RDPS who forget or who just don't care, Shield Lob has a range of just 15 yalms, and they will not, cannot wait for me to run into range and gather the mobs before they start laying down the smack.