I'm a "casual" too. I don't care at all about efficiency, spending gold, spending statboosters, babying or all that. I just care if a unit has good growths, good stats,
and is fun to train.
Tiki and Est aren't necessary to complete the game but they make my team much stronger. Maybe they just don't work out for you.
Are we going to argue forever?
One playthrough, I trained Est, Catria, Palla, and Tiki. I turned Est, Catria, and Palla into swordmasters. They were too awesome. All 4 of them on a team along with Linde(for a sage) were amazing.
I divided statboosters evenly so all of them had great stats
So you just don't like the Est archetype?
I always liked training units like Est and Tiki because late in the game everyone is usually very strong so it is fun to train units who are very low level
but have great growths and then watch them destroy everything in their path.
Well, units like Tiki and Est are going to be hard to train on the harder levels but on the easier levels they can be some of your best units when you train them enough.
If your units are already awesome when Tiki appears, then there is no point working on them so you can train Tiki a lot to be even more awesome.
Even if you don't arena abuse, you're units should be strong by the time you get her. If you don't want to train her, then don't train her, but she is a very fun unit to use.
If you give Tiki some levelups and statboosters her stats become much better plus it's easy to work on her since you can just arena abuse your other units and not worry about them.
One playthrough, I trained Tiki and Nagi (I tricked the game) and Tiki had much better stats because of her availability. I gave her the starsphere so her divinestone won't break.
When I was on chapter 22, I had Tiki solo the chapter and she had barely any damage.
Her stats with divinestones boosts attached can actually go above 30 for resistance and defense but the game only allows a maximum of 30 (search it up if you don't believe me).
I've used her in Normal, Hard 1, and Hard 2. She has 30 resistance, 30 defense, 30 strength caps. She's good in most of her stats but I use statboosters for HP, defense, strength, and resistance to reach those caps.