Alex could tell from the start that the two Daos were going to take him a lot of time to learn. Even with the incubating beast cores he was eating or even with Nightslayer right before him, it was going to take him a long time to learn the two Daos.
Alex wouldn't be surprised if it took him more than a few years for each one.
Unlike other Daos, Yang and Yin Daos were incredibly difficult to learn, after all. Instead, it probably would have taken him ages to learn them had it not been for the fact that his closeness with Yang was so good. Otherwise, learning them in a few years would be a foregone conclusion.
Alex considered his options once again, trying to see if there was something better he could do to speed up his cultivation instead of learning another Dao. Unfortunately, the only other good option lowered his lifespan. While he wasn't as averse to doing that, he thought it better to give this a try first.
