udging from the level you have posted here, I can assume you're still training at either Twisted Jesters, Ariant, or if you've figured it out yet, the sexy experience that is Iron Mutae. That said, I understand why you may think this. Generally at those levels, as long as your equips are decent a dark chain + blow skill will kill off sandrats/scorpions. A teleport mastery will finish them off otherwise. However, as you get into higher levels, advanced dark chain might be scoring 25K hits max. Just as an example, we'll take the Captain monster into account, since it is such a wonderful training spot.
Let's preface by noting that a Captain has 75K HP.
At level 105 you might be hitting 25K max with advanced dark chain and a critical hit. That'll leave 50K HP left for the captain. Your blow skill might do between 20K-35K. If you hit 20K with it, this still leaves an additional 30K HP left to take out. A second blow skill could possibly do it, but The Finisher, as I said previously, will come out faster and consistently do higher damage than the blow skill. The Finisher also has less lag -after- the Blow is used allowing you to telecast through or away from the Captain more quickly, allowing for higher training efficiency. Adv Dark Chain has a HUGE lag time after the skill is used before telecasting. Mobility is key for a BaM.