TL;DR: Use a shield when exploring.
I have around 700 hours logged and have spent a good bit of time in that exploring. I'd even say it is most likely what I have spent the majority of my time doing.
I explore in a Chieftain. Every since I picked one up at Jamison after getting Elite Explorer, I haven't really quit using it. I've tried other ships, but nothing really compares to the Chief for me. I ditched my 66ly AspX and started using the Chieftain instead.
Now, there is one really big issue with the Chieftain as an exploration ship. No, it isn't jump range. I think most ships are capable of the jump range to explore. Having a 70ly jump range isn't as important as most will make it out to be. I usually stay in the Inner Orion Spur or neighbouring sections anyways. What makes the Chieftain bad at exploration is the lack of internals, or the 3 class 4 slots for "military only."
This makes outfitting a little tricky. You have to make sure you are best utilizing every slot. You aren't doubling up on AFMUs. The best shield would be a 3D, but that has to go into a Class 4 slot. I like having a bot of cargo space, just in case. So, after getting the new double engineered FSD, I knew it was time for another trip. This time I decided to ditch the shield and get a cargo rack. I had never actually needed one, but it was kinda like a safety blanket. What if I come across something and don't have the cargo space for it?
I had pretty good success for a while. I got around 8k ly outside the bubble and was happy to find a guardian site to go to. This validated my choice of cargo space. I even found a fleet carrier parked near the system. This would give me a good chance to get my hull back up. When recalling your ship, the AI always seems to manage take a half a percent from the hull.
I was getting pretty close to my first big stop of the journey when I found a 1.3g planet with geological sites. That's great for me. I prefer 1ish g on a planet because the SRV handles batter and you don't have to go around catching all the materials.
I had landed on several planets over 1g to this point, with no issues or hull damage. This was just another stop on another planet to me. I had gotten complacent. Got in a rush to land. Hit the planet around 200m/s or so and destroyed my ship. Back to Jameson I went.
It's always after you get comfortable that you get caught out. This reminds me of riding a motorcycle. You are more likely to get in a wreck your second 3 months of riding than your first 3 months.
Lesson learned. Don't go exploring without shields.
Source: https://www.reddit.com/r/EliteDangerous/comments/lvie55/why_shields_are_important_for_exploration/