Serial Debug Logging vs Watchdog Timer for Diagnosing Failed Sketch Deployments on AVR Arduino Boards

Goal: Choose a diagnostic method that reveals why a sketch fails to deploy without consuming excessive resources or disrupting the bootloader upload process on AVR‑based Arduino boards.

Constraints: Serial‑based debugging adds flash and RAM overhead proportional to the number of log strings and can delay boot‑up when placed in setup(). The Watchdog Timer can automatically reset the MCU after a period of silence, catching infinite loops, but a timeout shorter than the bootloader’s ~1‑second window may trigger a reset before a new upload finishes, potentially corrupting the bootloader and requiring an external programmer to recover.

Uncertainty: Developers must weigh the immediate, human‑readable output of Serial logs against the automatic reset safety of the Watchdog, while also accounting for board‑specific WDT implementations (AVR‑specific avr/wdt.h versus SAMD21 on boards like the Arduino Zero).

Which approach minimizes impact on available flash and RAM while still providing useful diagnostic information?
How can the Watchdog Timer timeout be configured to avoid interfering with the bootloader’s upload window on classic AVR boards such as the Uno?