I want to buy another LEGO Technic set therefore I'm trying to analyze the challenge to price ratio of different sets. I first thought that the part count may be somewhat proportional to challenge and fun of building but the winner of this category is the 42069 set (extreme adventure) and this set seems to have a lot of tread parts which probably are included in the part count on the box so I was wondering if there is the "real part" count somewhere so my calculations are more accurate or maybe there are some reviews that include numerical fun factors or challenge factors that I can compare to price.
As you're finding, overall part count doesn't really reflect the difficulty or challenge of the build - for example the Minecraft Micro Worlds had about 450+ pieces each (a good 100-200 more than similar priced models), but most of these were 1x1 plates and tiles. LEGO already have a rough guide to the challenge of set in the age range: With variants from 8-14, 9-16, 10-16, 11-16, 12+, 16+, or in the case of the Bugatti, un-rated ;)– Zhaph - Ben Duguid ♦Jul 26, 2018 at 16:41
@Zhaph - Ben Duguid: Isn't that rated 16+?– LegoSonicBoyJul 29, 2018 at 11:28
@LegoSonicBoy Ah, yes, was in such small letters I couldn't see it in the promo box shots I found.– Zhaph - Ben Duguid ♦Jul 29, 2018 at 13:57
The "realest" of the real part count for any piece is always located somewhere in the back of the instruction booklet piece manifest.
Look at middle row last piece bottom, where it says we're gonna need 108x 6014648.
Wow, this thing looks cool! Have fun!!
Source: LEGO instructions - Technic - 42069 - Extreme Adventure (Model 1) by LEGO instructions - Fan - Site.