If you dont like to make the size when insert a door or a window, make a block out of it and the size is ready, ofcourse this will make it more cumbersome to make any change to it.
How to make this, insert a window/ door in the size, design etc. like you want in a wall, copy it out of the wall and make a block of the copy.
For changing the block, go to library palette Block, select the block and select "edit Block ", when in edit mode select the block and go to Selection Info ", do your changes and go back to Block Palette, finish "Edit block".
V20, V21, 2015/ 16/ 17/ 18/ 19 Pro. Platinum
Deluxe 2015/ 16/ 19
Windows 10 Home Premium 64 bit, 32 GB
NVIDIA Geforce GTX 780m, 1 GB