If you're otoing with the same methods that you used when you first started using UTAU, I'm not sure how well it would turn out, so you can always double check with this beginners' CV otoing guide.
https://utaforum.net/resources/cv-otoing-guide.269/
Another technique you could try is to record CV with a dummy vowel before every syllable, and OTO them as a sort of pseudo-VCV. This type of OTO is a connecting CV and is conventionally aliased as [* CV] (for example, [* か]). If you want your users to use them by default, you can use plain CV aliases instead.
View attachment 10885
In a VCV OTO, the overlap would be longer, and further left to cover the stable vowel. However in a connecting CV, the overlap is shorter (here it's only 50) and is positioned at the end of the vowel fading out. This means that only a tiny bit of the vowel is remaining and it gets completely crossfaded with the previous note. You will also be able to preserve the exact natural timing of consonants this way.
If you decide to use connecting CV, you will also need starting CV otos. You can safely assume that they'll always be at the start of a phrase and have no other notes before them, so it's very easy to OTO them and not have to care about overlap values or how much of a gap needs to come before the consonant. These are conventionally aliased as [- CV] (such as [- か]).
View attachment 10886
I used an overlap value of 10 to deal with UTAU's automatic envelope shape and placed it right at the start of the consonant.