Question: Is it alright to practise chanting at other temples or Buddhist centres, where ancestral tablets of deceased loved ones are not placed, while still benefiting them?
Answer: Yes, as dependent on the factors that follow… Unless there is clear sign of the consciousness of the deceased, if not yet reborn, to be attached to, or near the tablet, the deceased might not be there. When chanting, two powers are being offered – the power of guidance and the power of merits: https://purelanders.com/2013/11/07/how-to-share-the-power-of-merits-guidance
If the deceased is not around, only merits can be shared, while guidance cannot be given, as he or she is simply not there to hear it. Thus, to maximise efforts, it is best to chant where the deceased is most likely to be attached to. This might be a favourite place, such as home, or where the remains are.