"even if only once" is a correct and usable part of a sentence in written English.
It is typically used to express a condition or possibility, often with a sense of doubt or uncertainty. Example: "I would be happy to visit that exotic island, even if only once in my lifetime."
Even if only once a year.
To know they were right, even if only once.
Among the very few ideas that are generally accepted is that children X-rayed before birth, even if only once, have a measurably higher chance of developing leukemia.
In addition, others may have become infected from experimentation with drug use, even if only once decades ago.
Number of Sexual Partners is based on the answer to the question of "With how many partners have you ever had vaginal intercourse, even if only once?" The question was repeated at Waves I III.
Breastfeeding initiation refers to the baby receiving any breast milk, even if only once.
But even so, I was grateful that it was spoken, if only once.
Even if done only once it was done in a manner which should have caused diffusion of the tumor.
In a broad range of socioeconomic settings, modelling has demonstrated that screening, with treatment when necessary, is a very practical and cost-effective approach for cervical cancer prevention for sexually active women even if performed only once, around age 35 years.
In developing countries, prenatal care, even if only attended once, remains an important factor in obstetric care, as this may be a critical linkage between the woman with maternity care services [ 9, 28].
The bottom line is this: If you smoke at all - even if it's "only once in awhile" - you are at increased risk of cancer and heart disease, because the substances and carcinogens in cigarettes and tobacco are so concentrated and toxic.
