Well, like many other parts of PSIII, techs were desingned in a very careless way. The Healing Techs were too powerful in my opinion, the Melee Techs too weak and additionally there was rarely a battle where the use of Time and Order Techs was effective. I mean, instead of paralyzing an enemy, usually Wren or the main cahr could destroy it with one single attack. Order Techs were useful in boss battle but that was it. I guess all Techs could have been more useful if the battle were more difficult and required more tatics. The only tactic you had to care about so far was to heal your party in time. That's it.
The fact that some characters start with ridicoulisly low tech levels (for example Crys but especially Kara (warrior) isn't helpful either. It takes long to level the characters and if you do the techs often won't increase.
Yet, there were still some characters which made the use of techs quite effective. You mentioned Lyle before. I prefer him using Zan which is quie effective and Sean's Melee Techs aren't bad either. I like him using Tsu which can be quiete effective in several battles as well as his Zan probably can be. If you equip him with Swords his Melee Techs will become useful because they give you the opportunity to attack multiple enemies.
By the way, can it be that some techs are gender-specific ? I never saw a girl in PS III who could use Time Techs as well as I never saw a guy being able to use Order Techs?
@Myau: There are indeed some items which cast techs. I noticed this last year for the first time and I was shocked

I own this game almot 20 years now and it is still able to surprise me
