As an engineer myself I have asked this question many times. Yes, you should monitor the code. Let me explain.
The app itself whether paid or free with ads is what will give you a paycheck. If the code is not optimized for in production sources, there may be a flaw. If you catch the error or non optimized code you can point it out and make the app better. This will lead to the 4 steps of a good app.
1). Reliability
2). User Friendly
3). Compatibility
4). Sustainable Users
I call this the RUCSU blueprint. If you can optimize code, then always throw in a suggestion. If your suggestion is on par, then that's more users which means growth.
Depending on the what the code is for, your suggestion may make the app better and and more user friendly. Always check, then recheck the code for best optimization.