For me personally, taking into account whether or not a plane had power outlets is the overthinking option.
I've been on planes / trains / coaches that are expected to have them, but who had faulty outlets at my seat for that particular journey and I wasn't able to use them. So I just have a small battery pack (little bit bigger than a pack of cards), and a big one for laptop recharging, and I take one or both (plus my slightly bigger than a lipstick one that's light and fits easily in pretty much every clothing pocket I own) depending on the trip I'm going on, meaning no added complexity as it's just like remembering to take my laptop's power cable, and I no longer have to spend any time thinking about whether the transport will or won't have a power source for me.
I appreciate what works for me won't be the preferred solution for everyone, but for me it definitely leads to less overthinking per trip not more. (And personally I don't notice the added weight of these batteries in my bag; and I would want them for travelling even if I could be guaranteed every flight & train had working power outlets, as I've had times when they were useful to have when visiting a client's offices, or when staying in a hotel with a dodgy outlet, or when going hiking an nowhere near power outlets - so in my case it wasn't even an additional cost caused by not trusting planes to provide a good power supply.)
I've been on planes / trains / coaches that are expected to have them, but who had faulty outlets at my seat for that particular journey and I wasn't able to use them. So I just have a small battery pack (little bit bigger than a pack of cards), and a big one for laptop recharging, and I take one or both (plus my slightly bigger than a lipstick one that's light and fits easily in pretty much every clothing pocket I own) depending on the trip I'm going on, meaning no added complexity as it's just like remembering to take my laptop's power cable, and I no longer have to spend any time thinking about whether the transport will or won't have a power source for me.
I appreciate what works for me won't be the preferred solution for everyone, but for me it definitely leads to less overthinking per trip not more. (And personally I don't notice the added weight of these batteries in my bag; and I would want them for travelling even if I could be guaranteed every flight & train had working power outlets, as I've had times when they were useful to have when visiting a client's offices, or when staying in a hotel with a dodgy outlet, or when going hiking an nowhere near power outlets - so in my case it wasn't even an additional cost caused by not trusting planes to provide a good power supply.)