Congratulations Nikitachi!
I started writing this out after posting my score last night just in case it turned out that I needed to post my strategy. It's probably not necessary now but I may as well share it anyway...
My strategy was mostly based around two things:
1) making a lot of money quickly via a painting club & photography
2) minimising money lost to depreciation
After a little bit of practice early on, I realised that the main limiting factor was going to be money. Paintings, woodwork items and collectibles are all pretty quick to do and the unique fish likely wouldn't get time consuming until at least half way through. The potential profit from one $200k house would be equal to that from ten $20k houses AND the $200k house would only require 1 fish & 1 party (etc).
So making enough money to buy the most expensive houses asap was a top priority. I had planned to buy myself a different pack over the holidays but after confirming with the team that using clubs to make money was allowed, I decided to buy Get Together instead. The money making potential of a painting club is just too good.
My first two days were spent making money from the painting club & taking hundreds of photos; with a little bit of time spent on meeting the sims that I planned to evict in future when I wanted their house.
Testing in practice had revealed that the majority of build mode doesn't suffer from depreciation. So all significant lot value additions were done in build mode and I also decided that I would stick to unfurnished places until I could afford to lose $20 - 50k to depreciation on moving into a place. My first 4 lots were unfurnished, including Crick Cabana which I also turned into a tiny house for the skill gains.
Adding around $100k of lot value with build mode was a little tricky so I couldn't resist naming my sim after a fictional character known for being a terrible architect(*). A "Johnson special" in my game typically meant a basement, pool/s (usually in the basement) the most expensive wallpaper/flooring regardless of aesthetics or practicality (parquetry flooring in the pool..
), and - if necessary - way too many decorative balconies. Plus lots of easels out the front for the painting club.
(For some reason Johnson painted the same woman a lot. Even accounting for the fact that I had him stick to classic paintings, she turned up way more than any other painting. It amuses me to think of future residents/historians in this sims world wondering about things like "why was Johnson obsessed with decorative balconies & pools in the basement?" or "who on earth is this woman he painted so many times?"
)
Before starting I also spent a lot of time with Oshizu's Sims 4 Neighborhood Maps: All in One thread which is an amazing resource. My goal was to flip the 10 most expensive lots in my game, plus a few other places as well. The 5 most expensive lots were also deliberately saved until I could afford to take a financial hit from their furniture depreciation.
I was too sick to play for some of the time, so I only ended up getting though 1.5 game weeks (7 most expensive lots plus Crick Cabana & a few mid range properties). But I highly doubt that I would have reached the top scores anyway. I know that the week & a half that I did play was definitely not spent as efficiently as it could have been.
I was also aware that accidental mistakes such as forgetting to clear inventories could be an issue for me so I wrote myself detailed checklists both for a) before moving out of a place, and b) stuff to do immediately at the new place. I made myself check & double check these lists every single move and I credit this with saving me from becoming another one who DNF.
Happy to answer questions if anyone wants more details or wants tips about any specific aspects of the challenge.
*
https://wiki.lspace.org/Bergholt_Stuttley_Johnson