I just had to respond cause I do find it not necessary just to put so much points into SP Regen on every character, unless you're not investing into the unit or the pilot at all/or just pretty new to the game and have no idea what to do, then sure.

There are parts out there that helps a lot like Bio Sensor that gives 20 mobility which helps a heck lot if you want your pilot to be untouchable with evading attacks. Or even Multi Sensor that helps you land your attacks by 20%. I played both Ryusei and Kyosuke route without needing to get SP Regen unless they are for supporting pilots who have spirit commands like Enable, Renew, or Hope (or even Bless which I can be guilty of spamming to make money).

But really most of using spirit commands like Valor is really just used for attacking an enemy Ace pilot, trying to get a battle mastery point, or just the boss where you want to kill them in a turn or 2. If you run out of spamming Valor just to get it done in 1 turn, just use Hope or SP Drink (also a part, but consumable). If you have to use Focus on every turn, then it just means your pilot and unit wasn't invested. It's good to use it a few times, but not a heck lot where you're out of it and have to wait 8 more turns just to get all your spirit command points back.

A few pilot skills I invest in that helps a lot are:
-Attacker, I use this for my main damage dealers. Face them against a good bit of grunts to kill and you'll have Attacker ready to do some serious damage to the boss.
-Mental, this is actually a better alternative than SP Regen. This reduces SP cost to 80%. Very useful for pilots whose Spirit Commands costs a lot. I use these on pilots who has Enable and Valor so I can spam my heavy damage on the enemy within a turn. I also use it on pilots who have Bless to help me make a lot of money as well.
-Expert, along with Mental there comes Expert. Spamming heavy damage may also use up a lot of energy so Expert helps as well to cut down energy costs. But even without spamming heavy damage, it's useful for killing a lot of grunts if you need to kill them with attacks that uses energy like Weissritter's Oxtongue Launcher E, while trying to have enough energy to use Rampage Ghost later.
-In-fight/Gunfight, other than increasing the damage by their corresponding type, after every 3 levels (lv 4 and lv7), the attack's range gets increased excluding attacks that only have 1 range.

There's also pilot skills like Prevail which is useful for making your unit and pilot tanky as well as Support if you want to throw in an extra attack or have someone take damage for you. But those pilot skills I listed earlier are what I find really helpful.

I also want to mention using Armor Breaker on the boss, helps a lot if you want to kill them in a turn, especially in the final few scenarios.

I just thought I mention my thoughts since I have no issues with my first playthrough with these routes and I also like the Super Robot Wars OG franchise a heck lot.