That depends more on the material and what you are trying to do with it. If you are refluxing solvents, in general, the lower the boiling point, the more efficient or larger your condenser needs to be to keep all of the solvent in the pot instead of letting it escape through the condenser. If you are doing a distillation, the closer together the boiling points of the compounds that you are trying to separate, the larger or more efficient your condenser needs to be to get the separation.