Improve SKR mini E3 + Ender 3 settings (#16247)

config/examples/BigTreeTech/SKR Mini E3 1.0/Configuration_adv.h

    * STEALTHCHOP_(XY|Z|E) must be enabled to use HYBRID_THRESHOLD.
    * M913 X/Y/Z/E to live tune the setting
    */
-  //#define HYBRID_THRESHOLD
+  #define HYBRID_THRESHOLD
 
   #define X_HYBRID_THRESHOLD     100  // [mm/s]
   #define X2_HYBRID_THRESHOLD    100

config/examples/BigTreeTech/SKR Mini E3 1.2/Configuration.h

  * heater. If your configuration is significantly different than this and you don't understand
  * the issues involved, don't use bed PID until someone else verifies that your hardware works.
  */
-//#define PIDTEMPBED
+#define PIDTEMPBED
 
 //#define BED_LIMIT_SWITCHING
 
 
   //120V 250W silicone heater into 4mm borosilicate (MendelMax 1.5+)
   //from FOPDT model - kp=.39 Tp=405 Tdead=66, Tc set to 79.2, aggressive factor of .15 (vs .1, 1, 10)
-  #define DEFAULT_bedKp 10.00
-  #define DEFAULT_bedKi .023
-  #define DEFAULT_bedKd 305.4
+  //#define DEFAULT_bedKp 10.00
+  //#define DEFAULT_bedKi .023
+  //#define DEFAULT_bedKd 305.4
 
   //120V 250W silicone heater into 4mm borosilicate (MendelMax 1.5+)
   //from pidautotune
   //#define DEFAULT_bedKd 1675.16
 
   // FIND YOUR OWN: "M303 E-1 C8 S90" to run autotune on the bed at 90 degreesC for 8 cycles.
+  #define DEFAULT_bedKp 50.71
+  #define DEFAULT_bedKi 9.88
+  #define DEFAULT_bedKd 173.43
+
 #endif // PIDTEMPBED
 
 // @section extruder
 #if EITHER(AUTO_BED_LEVELING_LINEAR, AUTO_BED_LEVELING_BILINEAR)
 
   // Set the number of grid points per dimension.
-  #define GRID_MAX_POINTS_X 3
+  #define GRID_MAX_POINTS_X 5
   #define GRID_MAX_POINTS_Y GRID_MAX_POINTS_X
 
   // Probe along the Y axis, advancing X after each column

config/examples/BigTreeTech/SKR Mini E3 1.2/Configuration_adv.h

      *
      * :[ 'LCD', 'ONBOARD', 'CUSTOM_CABLE' ]
      */
-    //#define SDCARD_CONNECTION LCD
+    #define SDCARD_CONNECTION ONBOARD
   #endif
 
 #endif // SDSUPPORT
 // The number of linear motions that can be in the plan at any give time.
 // THE BLOCK_BUFFER_SIZE NEEDS TO BE A POWER OF 2 (e.g. 8, 16, 32) because shifts and ors are used to do the ring-buffering.
 #if ENABLED(SDSUPPORT)
-  #define BLOCK_BUFFER_SIZE 16 // SD,LCD,Buttons take more memory, block buffer needs to be smaller
+  #define BLOCK_BUFFER_SIZE 32 // SD,LCD,Buttons take more memory, block buffer needs to be smaller
 #else
-  #define BLOCK_BUFFER_SIZE 16 // maximize block buffer
+  #define BLOCK_BUFFER_SIZE 32 // maximize block buffer
 #endif
 
 // @section serial
 
 // The ASCII buffer for serial input
 #define MAX_CMD_SIZE 96
-#define BUFSIZE 4
+#define BUFSIZE 32
 
 // Transmission to Host Buffer Size
 // To save 386 bytes of PROGMEM (and TX_BUFFER_SIZE+3 bytes of RAM) set to 0.
 // For debug-echo: 128 bytes for the optimal speed.
 // Other output doesn't need to be that speedy.
 // :[0, 2, 4, 8, 16, 32, 64, 128, 256]
-#define TX_BUFFER_SIZE 0
+#define TX_BUFFER_SIZE 32
 
 // Host Receive Buffer Size
 // Without XON/XOFF flow control (see SERIAL_XON_XOFF below) 32 bytes should be enough.
    * STEALTHCHOP_(XY|Z|E) must be enabled to use HYBRID_THRESHOLD.
    * M913 X/Y/Z/E to live tune the setting
    */
-  //#define HYBRID_THRESHOLD
+  #define HYBRID_THRESHOLD
 
   #define X_HYBRID_THRESHOLD     100  // [mm/s]
   #define X2_HYBRID_THRESHOLD    100