with groups being based on total levels, finding a group before level 40 can be hard and heres why i think it is
consider yourself to be a 1x20 with no other levels than 20 in your prime level you finally get a group with someone but he has 4 classes at level 20 and hes also level 20
the person with 4x20 levels would receive a substantial amount more in exp per kill and the person with 1x20 would basically receive almost nothing since he has basically 4 times more levels than you
as another example lets say your around level 35 with all other classes up to your quad class to level 15(total level 80) and nothing else and you group with a level 30 who has level 25 classes up to quad and 5 in each after quad (total 125) the level 30 has 46% more levels than you do so he will gain much more exp despite being level 30
as my examples sound silly i would like to show real life examples on the who list on people differentiating in total levels but have the same or higher prime levels
prescience a level 20 has 101 total levels (not that far from the level 30 in my example) grouping with umaro at 61 total levels there is roughly a 40% difference in levels
and if you group prescience up with a level 38 zenoko (total level 91) youll notice prescience actually gains MORE although not a huge amount more exp than zenoko despite zenoko being a level 38
some people may ask "why not just get your sponge levels and close the gap?"
some classes like mage druid and necro i think (just me) would want to rush their prime levels to get the biggest nuke(mage), get the best shapeshift form(druid) more summons/also more powerful ones(necro) and while they do this their other levels become skimpy causing others their level (and sometimes lower) to out exp them in groups to a point where soloing is a lot better than grouping
people have tend to also blatantly rush their levels for a skill/spell (like stone skin,sanctuary,circle, etc) forgetting all other levels
what i suggest to do (and this can be debated) is
-base the grouping exp formula on prime levels for everyone whos not a level 40 prime or higher to encourage lower levels to group with others at similar prime levels but much higher total levels while keeping the group exp formula after level 40 prime as total levels