I personally believe that putting good systems in place helps mentality, even if things might not go in your preferred direction, if you have good systems in place, including being both financially and mentally prepared for either price direction, and you are able to act upon movements in either direction, then your ongoing actions in light of anything that happens are likely going to contribute towards your being (and feeling) mentally stronger.
A good plan or as you would put it "a good system" is the only way that one can get his holdings secure and avoid certain drama's and distraction that might lead to tempering with his holding, although such drama's are inevitable in life so only a good system can help you evade or adjust so that much effect won't be on your side. But I would also like to point out that setting a good system isn't just going to cut it as one would still need a certain amount of discipline to actually execute or make this system active because I believe most people lack discipline in sticking to the actual plan and that's the main reason for many Bitcoin investor actually not holding till the end but a good system helps limit the amount of self discipline because a good plan and a keen mind is what is needed as a Bitcoin holder.
It may largely be a semantical difference since I think that I consider one of the differences between having a plan and a system, is that the idea of a system implies the existence of a plan that might get tweaked from time to time under certain criteria, and it also implies ongoing putting the plan into action and trying to learn from mistakes.
I have no problem with the acceptance that aspects of a plan might have some rigid and structured areas, and then other aspects will have more flexibility and there may well be acknowledgements that the system might not be perfect but it is fitting for the current circumstances, and maybe even when it is changed, it is ONLY tweaked here and there.. but there might be stages in which more major changes might be justified.
In my attempts to follow my own systems, I frequently will find myself making the larger of adjustments after large price moves have occurred, and so sometimes that might be the implementation of a kind of bigger change, and then letting it run for a month or two and then revisiting whether that BIGGER change is working very well.
Maybe an example might be helpful, here.
In early 2022, I had buy orders down to about $21k-ish, and then in around May 2022, the BTC price broke quickly below the 100-week moving average from $37k-ish down to right around $30k-ish, and I realized that if all of my buy orders filled down to the lower $20ks, I would not have any cash left. So I made adjustments to them, and then when the BTC price broke down in to the lower $20ks I made further adjustments, and I ended up making several adjustments during that time to ultimately get my buy orders to go down to $13k-ish, and part of the idea was that it was not expected for the BTC price to break down below the 200-week moving average so quickly (which was then right below $22k), and once it did several adjustments had to be made to continue to buy and not to panic, and surely there were some folks who sold during that time and some of them were able to buy back in and some of them were waiting for $10k to $12k or even below $10k that did not end up happening.. So we cannot necessarily determine how each person is going to deal with the situation and whether one thing is better than another, and so I did not really start to feel good about my having had made it through the whole thing until the BTC price got back above the 200-week moving average in early 2023, but then there still was some uncertainties about whether the $15,479 bottom was in or not.. so there still would be quite a bit of guardedness, and some ways of dealing with these kinds of times worked better for some folks than others including their finances and/or their psychology..
and surely my assertion is that if you have good financial systems in place psychology will follow and usually I do not worry too much about BTC prices because I have orders set up to buy if the price goes down and to sell if it goes up, but there were a few days in June 2022 or so that I had to cancel my other social engagements until I figured out how I was going to deal with the BTC price continuing to drop, including that it had gotten down to around mid $17ks at that time, and it was not clear whether the dips were going to stop or not.