Sorry for the long post
I am a very instinctive trainer but it varies. I always follow a training plan as in what body parts I am training and when you do that for long periods you end up doing very similar workouts even if you decide to do what you want vs following an exact sequence of movements. It's the same with my diet and I eat what I want but that is pretty much the same stuff day after day. As you already know you should have a plan to attain your goals so you can be an instinctive trainer in addition to following a set training split. You have guys who logbook training and some will just do working sets for a few main movements and some may even count every single set they ever do. I don't do any of that but I have my logs online and of course I know how much weigh I have lifted last week from memory so I always try to progress I just do it more over a gradual time period and not workout to workout.
When I walk to the gym I know what I am training because I follow a training plan and I usually stick to each plan for long periods. However, I usually decide what movements I am going to do as I walk to the gym. They differ workout to workout but over a period of time (week to week) I pretty much do the same movements 90% of the time. I prefer having some freedom in there though. Sometimes I am training and I may do 1 working set and other times I do a drop set or similar... non of that is usually planned and it's on the spot. I done leg extensions for 7 controlled reps going up a plate a time with no rest the other day and that was made up as I started lifting the weight and was on about the 4th warm up rep. Last time I went to the gym I only had 1 hour so on the way to the gym I planned out my exact routine. When it was time to do chest press the machine was taken and I could have waited but I used a different one so nothing is ever written in stone with me.
As stated I tend to do the same things so there is a rough template in mind when it comes to training movements. I usually do laterals and front raises then a press and for chest I like to do a fly, press then repeat or something like a dip. Right now for pull I am rotating stiff leg deadlifts with the glute drive machine workout to workout. I usually go top to bottom when training back as well. Legs I do calves, hams, glutes and quads 90% of the time. I have my main movements but I often add in something different workout to workout.
Anyone can do this but instinctive training is best done when you have a decent knowledge of body mechanics and movement patterns. So you can rotate very similar movements in if you can't or don't want to do your planned exercise. Another way I change training is also rep ranges and sometimes after many weeks of 6-15 reps I may add in a high rep only day because my body/mind is telling me to. I never plan deload things though. I should also state I do PULL and PUSH now but there is no set pattern as in on, on, off etc. I train when I feel good and I have a break when I feel bad but it usually works out with 4-5 days per week most of the year.
So for me I have a clear training plan. I aim to progressively get stronger but over a period of time and not forcing it workout to workout. I usually have a set routine in my mind but I will often change that on the day. It could be changed to prevent waiting for equipment but it's usually just because I like to change things up slightly from time to time.
I will say I think logbook training is extremely effective and I would recommend it to everyone who wants to grow as much as they can. However, there is only so much stronger you can get even if you force things. It's not like you won't get just as strong in the long term training the way I do. I see many force things meaning their form changes to hit a new number. That isn't necessarily a bad thing as long as their form is still good but it's not like they are chest pressing 12 plates a side because they tried to go up over years and use mini plates to add weight. The smallest plate I usually add to anything is 10kg so non of this 0.5kg stuff so I move up in weight this week.
There are limits to everyone and after so many years you will pretty much hit them regardless how you do things. I have always tried ot get as strong as possible and I have pushed myself to the max just not in a logbook fashion. I have done 10 pps hack squats with good form and 5pps smith presses etc so I have still gone as heavy as I can I just don't logbook anything and I don't count reps workout to workout. I fail when I fail and I couldn't case less if that's 3 reps short of last week. Obviously logbookers would state but that is an effective way to know you may need to change the movement or a deload or x, y and z. I don't really put that much thought into things day to day. Fact is I am much weaker now then I was 10 years ago and I look a lot better so whilst strength is extremely important sometimes people forget this is bodybuilding and not powerlifting.