This is a good question.
The Sanatana Dharma puts most importance of Sraddha.From Kathopanishad(Sraddha arose in Nachiketa's mind) to Bhaktirasamritasindhu (Pu. Pr.La. 11) of the Gaudiya Vaishnavas, the primary requirement of all spiritual activities has been mentioned as Sraddha. In Gita, Sri Krishna repeatedly mentions the His preference for Sraddha.In sloka 17 of chapter 16, He says:
Self-conceited, haughty, filled with pride and intoxication of wealth, they perform sacrifices which are so in name only, with ostentation and regardless of the injunctions.
So we must put our best efforts to follow all the rituals, religiously.
But our capacity is limited and our Indweller knows it fully well.
So at the end of the puja, we chant a mantra that we get in the Puja-paddhati books:
jad asangam kritam karma jaanataa baapi ajaanataa/ saangaam bhavatu tat sarvam twatprasdat Sureswra/Sureswari
meaning O God/Goddess, let whatever has been improperor incomplete knowingly or unknowingly , get fulfilled by your grace.
The presence of this very mantra means that if we may have to keep some aachara incomplete or undone knowingly, because of some limitations and God makes everything Purna by His/Her grace.Because it is our inner feeling that matters, as says the sloka(Naradapancharatra,1/10/39)
Murkho vadahati Vishnaya dhiro vadati Vishnave/ ubhayos stulyam artham cha bhavagrahi Janardanah//
meaning an illiterate utters mantras wrongly and a scholar rightly. Both are equal to God as He accepts only our love.