The freeze duration of the shard is 3secs which is enough for one elect/tesla attack. One disadvantage of shard is the lower accuracy of it.
You need to specify which kind of target this combo is used against because:
1. If used against a 1 HP bar mob, your words hold true.
2. If used against a multiple bar HP mob, shard allows for 2 ticks of tesla and another filler [elec] move.