As a non-native English speaker I am not sure about the word order in sentences with adverbs when used in the "in-between scenario" (according to https://english.stackexchange.com/a/9602/9579). In this specific case, is it correct to say
I always should test...
or
I should always test...
The adverb is in both cases between subject and verb, but the tricky bit here is that the verb has two components ("should" and "test"), making two in-between scenarios possible...