I think this might be too specific and too vague at the same time; cellular network implementations become mind bendingly complicated pretty quickly - see e.g.:
https://helpfiles.keysight.com/csg/89600B/Webhelp/Subsystems/lte/content/lte_overview.htm
And so I think it is not easy and potentially misleading to be so specific (in this case 1.2Mbps timeslots) and to make a reasonable generalisation (in this case chopping off into timeslots to spread out load between users).
I think it is safe to state that the bandwidth a 4G user experiences is variable and dependent upon a number of factors like signal quality, network operator restrictions and the load on the connected cell tower.
As @moeller0 points out @professor_jonny, cake-autorate:
has been designed for exactly situations like this. It certainly works well on my own 4G connection and we have lots of positive reports and data showing its efficacy from other users accumulated over the last few years.