Contact-based metrics such as contact time, inter-meeting time, first passage time, etc. between mobile nodes critically decide the performance of mobile ad-hoc networks (MANET). Based on various mobility models, current theoretical studies have investigated the relationship between characteristics of underlying mobility patterns (e.g., domain size, degrees of correlations in trajectory, etc.) and stochastic properties of contact-based metrics (e.g., exponential and power-law behavior, aging properties), especially of the inter-meeting time. In this paper, we first review several interesting aspects of these results, including invariance property of contact-based metrics, as well as aging properties of the inter-meeting time. We then point out how these results can be further extended to guide the analysis and design of MANET.