Critique / improve my ridiculously slow XP progression table... xd

I am doing a thought experiment. I imagine up to half of the people here fall into the following camps:

-You feel the sweetspot for playing OSR style D&D tends to happen from level 1 to 6 about, those are often the most challenging and fun levels for they player while being the easiest to DM, hence often the most fun.

-You run/follow an OSR system or old DnD edition in terms of max. level cap and level progression, and plenty of OSR or old school rules cap the maximum lvl one can reach at 6 or 10 or advocate for a much slower progression than 5e.

I didn’t really want to have a truly fixed maximum level cap, instead I am simply making it very hard to level past 6th, but not impossible, since some groups do stay together for 5 or even 15 years,… The idea is that every level also truly means something, it was earned, with a lot of actual IRL investment, time and commitment. It also piqued my curiosity/I did notice that quite a few of those groups that have been playing together for years or even decades use old rulesets/very slow progression, perhaps it is a bit of feature for grognards or “hardcore” players that levelling be hard and takes much time.

Of course if I was to integrate the table below or something similar into a rule-set I actually published I would totally add that it is a suggestion and for people to feel free to adjust the things below to only one third for example, but that as a general suggestion, I am giving the totals below, in order to have a challenging, grim dark ish and hard game.

To make things a bit more doable and fun, usually if a player wishes to change character class/or character, I will let them if it is not often/for a good reason and I start them off 1 or 2 levels lower than the other characters, same thing if their character dies and they make a new one. So it is not like they start from square 1 every time/are wildly squishy and underpowered by comparison to their party members.

So my questions to you all are:

  1. Do any of you have a similar level of slow progression or hell naw, not even close in hours needed to attain the higher levels, what is your system or preference?

  2. At what level do you cap, what is the maximum level attainable in your game, if any?

  3. If you were to use something a bit akin to my table below, what would you change or lessen, half the needed totals beyond level 4 or 7 perhaps or…?

                    Total XP needed       Suggested hours of play-time needed

Level 1. 0 XP 0 hrs
Level 2. 20.000 XP 20 hrs = 5 sessions of 4 hours each
Level 3. 40.000 XP 40 hrs = 10 sessions of 4 hours each
Level 4. 80.000 XP 80 hrs = 20 sessions of 4 hours each
Level 5. 160.000 XP 160 hrs = 40 sessions of 4 hours each
Level 6. 320.000 XP 320 hrs = 80 sessions of 4 hours each = 1 year, 7 months
of playing every single week…
Level 7. 640.000 XP 640 = 160 etc
Level 8. 1280.0000 XP 1280 = 320 etc
Level 9. 2560.0000 XP 2560 = 640 etc
Level 10. 5120.0000 XP 5129 = 1240 sessions, if you played 4 hrs every week without fail,
still takes almost 25 years, and this is highly unlikely.

Etc etc up to lvl 20 or beyond

This means going beyond 6th, much less 10th is possible but extremely hard because it requires a lot of time (years) in the real world, by design. Having your character live that long and playing that often is very unlikely, but it could be done, especially if a group at one point gets access to 1 wish spell or 1 resurrection or such…