I know of someone who has spent a couple of decades praying and studying the Greek Orthodox Church & Roman Catholic Church both current authors and ancient fathers trying to decide which of them is the “True” Church and during that time has converted to both at different times and has admittedly failed to progress spiritually because of the overwhelming confusion and going back & forth. The priests in each tradition, naturally, have advised theirs is the " True" Church and is what should be attended. This person even tried multiple different Eastern Catholic Churches through out the years.
With the recent visit of the Pope to the Ecumenical Patriarch and with Roman Canons allowing inter-communion, this person had revealed to me that they’re is seriously considering forgetting about which is “True” participating fully in both Faiths.
The question is, for someone stuck in this situation for decades, can they, or should they, simply be in full communion with both by regularly going to Confession, regularly attending both Mass & Divine Liturgy, maintaining stricter of the Fasts, attending holy days in both, keeping the Prayer Hours, daily praying both the Rosary & Jesus Prayer - essentially just fully practice both Faiths daily (so progress in each could be made) rather than continuing to do a 180 toggling back & forth every few months? Why, or why not?