I think so, yes. Either 6- or 10mm for visual effect but I have participated in games with army corps (typically two divisions per side) where 15- and 20mm figures have been used very effectively. It is not so much the size of the figures but the ground scale that helps most. WW1 had more dense troop concentrations than WW2, by an order of magnitude. Infantry companies fought on frontages that were held by platoons in WW2 for example. Yet the long range weapon systems, including static machine guns, operated at the same sort of distances. In skirmish games you see a WW1 squad, sometimes a platoon, on table along with HMGs. The latter would have been at least two or more tables away according to ground scale. This makes it hard for gamers to appreciate why very wide frontage attacks were needed.
Robert