Like I have already previously stated, this is dependent on which rom you are using, how you booted to recovery and/or how you flashed twrp.
If you are using the stock rom, flash using odin and boot to recovery using the key combo you shouldn't have this issue.
Once this issue starts because of any of the 3 above or you have installed a previous recovery built by someone else which caused this issue then simply reinstalling this recovery will not fix the issue.
You will need to go back to stock first or flash the stock recovery then install and boot to twrp as advised.
I will not entertain issues reported involving flashing twrp with third party software, rebooting using anything other than the hard keys or using a non stock rom as any one of these can cause issues.
confirmed..
if you previously have issues booting into system because after every boot it always boots to (TWRP) recovery then you need to follow these steps:
1. reflash the stock rom using odin
2. boot back into download mode and flash OP's recovery WITHOUT checking the autorestart on the odin
3. after flash done, restart the phone by pressing and holding VOL DOWN+Power+Home button
4. when the screen turns blank, quickly press the key combo to enter recovery VOL UP+Power+Home button
5. done, you only need to re-root, re-debloat / re-freeze unused apps you have applied to your phone
CAUTION:
1. if you use supersu and it needs to update binary, just use normal mode from inside the system or use latest version flashable zips from recovery. other binary update mode will break the recovery booting behavior, and your device will always boot to recovery after every restart
2. flashfire/flashify reboot to recovery may also break the normal recovery booting, avoid these features and boot to recovery manually