The one-move chess problems on my website were constructed deliberately to be the "vocabulary" of chess tactics. I have long felt that learning chess is a bit like learning a new language. In these problems, you can find every motif like pins, forks, skewers, removing the defender, and mates.
I attribute the 1, 2, and 3 move problems by themselves to raising my rating from 1800 to 1900. Since I played a great deal of speed chess, my goal was to be able to see the tactical motifs as quickly as possible. Because I did these problems repeatedly, I got some criticism from one of my friends who said that I wasn't doing tactical problems, but I was memorizing them. This was partly true. My counter was that I could not memorize all the problems, but I could memorize the tactical themes. When I do the problem now, the tactical themes become quickly apparent. Likewise, I see tactics quickly in speed chess games.
A bit of history...
When I moved to Utah in 1993, I was around a 2000-rated player.
However, at that time the ratings seemed to work differently in Utah. Salt Lake City and the Wasatch mountain range are hundreds of miles from the nearest major metropolitan areas. It felt like the pool of rated chess players was isolated from other players by distance. When I started playing in tournaments in Utah, I saw my rating decline to 1800. Also, those players who would go to out-of-state tournaments, such as in Vegas, reported doing very well against similarly rated players from California.
I think that whatever difference there may have been balanced out some over time. There was nationwide rating inflation that happened in the 80s which my rating benefited from. This was due to the USCF tinkering with the rating system in the 80s and then reversing course in the 90s causing a noticeable rating deflation.
I constructed my online tactical problems around 1995 to 1998.
I don't remember exactly when I started studying the following materials:
Sharpen Your Tactics
Chess Pocket Training Book: 300 most important positions
Practical Chess Exercises
The 1000 problems on the Shredder iPhone app.
I spent 10 minutes every night for a year without fail studying the Chess Pocket Training Book, and then afterward had one of my greatest chess tournament results ever. This was 20 years ago.
So I attribute these materials to raising my rating from 1900 to 2000. Once again, I did a great deal of repetition. The goal has always been to make hard things intuitive. For me, this feels like learning a language.