Hi,
When you specify input sequence to Simulink you need to use a time vector and a data vector. So the vector only needs points where you want.
For example, The first column (0, 60*60, ..) corresponds to the times and the second column (T1, T2, ...) may correspond to the values at those times.
You can choose whether you want to interpolate between the values or hold them until the next reading. Thus, in the graph, there are no new values to plot, so its holding on to those.
See this for details on simulation time: