How often should I water my tomato seedlings to ensure optimal growth and development? Is there a specific frequency that balances moisture retention without leading to detrimental overwatering? Considering the delicate nature of young seedlings, what are the ideal moisture levels that promote healthy root systems? Furthermore, should external factors, such as temperature fluctuations and humidity levels, influence my watering regimen? As a novice tomato cultivator, how can I discern between the signs of under-watering and over-watering, particularly when seedlings exhibit drooping or yellowing leaves? In addition, could the type of soil, as well as the size of the pots, play a significant role in determining their hydration needs? What techniques or indicators exist to ascertain when my tomato seedlings require water, and how do these standards vary throughout their growth stages? Is there an optimal time of day to carry out this vital task for maximum efficacy?