Different Timing for Sehri

Asalamuakaikum. 
I wanted to confirm my routine in Ramadan has been permissible the whole time. A saathi today sort of distracted, and placed doubt in my heart as were discussing why the ‘Ulema are not unified in having one timetable for sehri.
I follow the sehri timetable of one Hanafi/Deobandi mosque because it makes life easier for me, but I break my fast, and perform Taraweeh with another Hanafi/Deobandi mosque because that’s where I graduated. Is this permissible? For me it’s no different performing salah with a mosque where the Jamat time is easiest. 
The saathi was claiming, one should follow the mosque in both sehri/Taraweeh, that he considers his local mosque? Surely this is a principal on good faith, but not mandatory?
I would appreciate your input.
Jazak’Allah!