Originally Posted by
Pex
The only thing wrong with stacking Extra Attack is it means a 10th level 5/5 warrior/warrior gets 3 attacks where a single class fighter has to wait until 11th level. Fix that discrepancy and all is well. The easiest solution is give fighters their third attack at 10th level. It won't be that difficult to balance in reference to the other warrior classes if any correction is needed. Ignore spellcasters. This doesn't affect them at all.
I do like the idea of stacking the number of attacks by total character level similar to the idea of stacking spell slots when multiclassing spellcasters or single class spellcasters. Then just give 11th level fighters something else that's Nice.