Business processes are typically supported by information systems that log execution data, enabling the prediction of remaining time for ongoing process instances. Deep learning models are often used for this task due to their accuracy, but they only provide point estimates, without accounting for uncertainty. This limits their reliability, as decision-making often benefits from prediction intervals. Uncertainty quantification techniques can help by estimating both expected values and uncertainty. However, existing techniques are often poorly calibrated, computationally expensive, or not adaptable to different deep learning models. This paper examines these challenges and proposes a simple, efficient solution using Laplace approximation and calibrated regression. Our approach distinguishes between model and data uncertainty, integrates easily with any deep learning model, and can be applied to pre-trained networks. Benchmarking on 10 real-world event logs shows that our method matches state-of-the-art performance while significantly reducing training and inference time. This makes it a strong yet simple baseline for uncertainty-aware remaining time prediction in business processes.