The example is designed to work with a single input waveform, for example, an actual capture or a synthetic waveform. This allows the example to be used immediately by people without ongoing access to data acquition hardware. Often users will have sets of offline captures or test waveforms rather than online hardware.
In terms of content and functionality, the example was intended to show the initial stages of LTE system acquition (sync and cell ID, MIB and then on to SIB1 PDSCH) and some of the minimum bandwidth requirements for these steps and the reasons behind them.
You are correct that, to perform all the processing steps on a single capture, in the general case, the data in the file would have to have been acquired at the full carrier bandwidth. If only the sync and cell ID steps were required then a narrower capture bandwidth could be used. If you have access to measurement hardware then, given on the device capabilities, it could be possible to dynamically reacquire data at different rates, depending on the processing stage.
