To be sub4 and sub 3 just practice and excelling in sarah advanced and algs is needed
To be understandable :_
1.) Make your sledges and hedges super fast sub 0.35 stackmat nd faster
2.) make your sledges to hedges transition fast and faster
3.) Learn good algs and watch videos of skewbers who teach algs that are better like carter kucala , elias molongere or skewb school
4.) Plan your first layer in inspection and make it sub 1 or sub 0.85 on stackmat
5.) Have a smooth and fast transition from first layer to last layer
6.) Keep practicing and experimenting (solves )
7.) work on one looking most solves or atleast half of them