Higher leveled characters(Maplestory powerleveling) (80-90+) may train better at monsters which require more hits, such as Death Teddies and Spirit Vikings, because of Area Effect attacks. Spawn rate sometimes depends on how many people are on a given map. The more people on a map the higher the spawn rate becomes, termed spawn acceleration. By the same token the opposite is true: the less people on the map the worse the spawn rate becomes.
It is advised that players seek other players of a similar level(MapleStory Mesos), given that parties of 4+ affect spawn rate. Since each player gains exp from each others' kills with the addition of a 10% EXP bonus, you should be able to level faster in large groups. In the case of maps with fewer numbers of monsters, soloing may turn out to be more advantageous. We got the Maplestory information from other website.