Some Mixing Desks wire the tip as send and the ring as return whilst others work the opposite way. It is safe to say there is no standard for this.
Whilst it is common to use this standard type of lead for inserts of outboard, larger consoles do not tend to use this method. Instead, they will use 2 XLR's for a fully balanced send and return. It is sometimes questioned how much of a difference this can make audibly for the extra expense, especially with such short cable runs.