Signal is a wide definition of possible traces. Signal can be status LED toggling every 3 seconds, it can be I2C in kHz range or SPI running 80 MHz or 100Mbps Ethernet. I don’t mind routing slow signals over power plane. For the fast ones I would go through pcb and route over GND plane with equal vias amount for each trace. So classic signals/GND/(split)VDD/signals is absolutely fine for simple applications.