Hi Trevor,
Yes typically we advise one source of data (accounting ledger being one) one transaction list.
Which will grow over time.
Even if your GL comes from different ERPs, I'd suggest striving to load them in the same TL (unless they are completely different and the mapping & transfos you need to do are wildly different).
One thing you can do, to increase clarity of your TL over time, is to duplicate it as a new year start and store the historical years in the duplicated TL while keeping the main one fresh of only the new year.
You’ll have to modify the metric that aggregate from your TL to take the duplicated one into account but that shouldn’t be too long