You should work with as much as is necessary for the studies. If you cannot obtain enough yield from 1 synthesis, then do 2. If 2 is not enough, than do 4. If 4 is not enough, find a more efficient synthesis method.
It usually is a balance between several aspects, (e.g. labware saturation, adequate recovery volumes, concentration/solubility issues, kinetics, etc.).
Optimizing altready existing protocols that were developed by someone else (or at least asking questions about it) is usually a good idea.
Conversely, if you came up with a protocol, get the opinion of other people on how to make it more efficient.