Heroes of Might and Magic III YouTuber and Twitch streamer TheKnownWorld presents a short and sweet argument for using multiple heroes, backed up by clear comparisons and helpful tips.
One especially hard-hitting point in the video is the day 3 treasury comparison between the single- and multi-hero examples: even though hiring extra heroes costs 2,500 gold apiece, the faster rate of exploration and access to more loose resource piles means that the multi-hero approach largely pays for itself.