While I don't necessarily agree with the 20-30 seconds of no action, its more a preference in tactics than outright opposition.

My preferred approach is a slow ramp up of DPS. Give the tank a few seconds to get his main enmity builds up (as an example, MRD getting their parry buff then setting off key abilities like defender and sunder). After that brief exchange the DPS classes start slow. ARC shouldn't go immediately to their multi-buffed multishot but instead use quelling strike and light shot a few times. Mages with rank 1 of their nukes. Etc.

My reasoning here is a matter of efficiency more than anything else, yes it may be 30 seconds out of a 5 minute fight but its still 30 seconds. You shave that many more seconds between the time the tank runs out of mana to self heal and the CNJ kicks into their own heals and the end of the fight.