ReadingDoctor Apps focus on different skill sets and should be used as part of a well designed synthetic phonics program.
The following general order of use is suggested:
Letter Sounds 1 Pro > Blending Sounds 1 Pro > Spelling Sounds 1 Pro > Letter Sounds 2 Pro > Sight Words 1 Pro
Some movement back and forward between the apps is appropriate and students will benefit from practicing earlier skills for revision.
The Word Builder App is a tool that can be used throughout this suggested progression, after basic letter sound knowledge has been established (e.g. after Letter Sounds 1 Pro).