It's rarely worthwhile to have more than 2 Techniques. 3 Techniques is going to have a price comparable to getting a +1 to skill (many Techniques are Hard; +3 to three such would thus cost [12], the same as +3 to skill), and 4 Techniques always costs
at least as much as a +1 to skill. It's even worse for combat skills, where almost all Techniques are Hard, and where actually buying up skill also improves your Parry. Heck, when you factor in Parry, even 2 Average Techniques aren't worth it - +2 to each and +1 to Parry costs a total of [9] ([4] for Techniques, [5] for Enhanced Parry), while just grabbing +2 to skill and getting the +1 to Parry for free costs only [8].
This assumes you have high enough skill for further boosts to cost [4] per +1; if you aren't there yet, you're pretty much
always better off improving skill over picking up even a single Technique. The only exception to the above is when you have Techniques that can actually be applied
together - Dual Weapon Attack can be worth it even if you already have 2 other Techniques, as can Counterattack, as those can be combined with things like Targeted Attack (although note you still need to be in the [4]/+1 range before even these become economical).
For characters who should have a wide variety of Techniques, I feel my
Tech! option is fairly well balanced.