First, you can multitrack record using Waves. If you want to do this, then using tie lines is the best option – just as it is with other recording methods. Otherwise if you are just using Waves for effect racks, you will generally insert those racks into the individual channels, groups or busses. You would not use tie lines in this case.
If you end up doing both (recording and effects) then you will likely use a mixture of both – tielines for recording and inserts for effects.