Sometimes. I am currently learning German, Italian, Spanish (reluctantly), Dutch, Turkish, Portuguese, Thai (trying to, at least), and Klingon (and I'm hoping to find a way to learn Arabic), but I can sustain a good conversation in German and Italian, and I will occasionally think of the word for something in one of those languages, like "anatra" instead of "duck", and if I tried to impersonate Germanyball, I would eventually just be speaking full German. I also rarely count in English. I know how to count to 10 in English, Spanish, German, Italian, Dutch, Klingon, Arabic, Russian, and Chinese, and I'm trying to memorize it in Thai and Korean. When I count things in my head, I often count in either German or Arabic if I don't expect to be counting any higher than 10 (12 is the highest I can go in Arabic ['ahad 'ashar]).
By the way, in case you were wondering;
German; Eins, zwei, drei, vier, fünf, sechs, sieben, acht, neun, zehn.
Dutch; Een, twee, drie, vier, vijf, zes, zeven, acht, negen, tien.
Spanish; Uno, dos, tres, cuatro, cinco, seis, siete, ocho, nueve, diez.
Italian; Una, due, tre, quattro, cinque, sei, sette, otto, nove, dieci.
Arabic; Wahid, ithnaan, thalatha, arba'a, khamsa, sitta, sab'a, thamaaniya, tis'a, 'ashara.
Klingon: wa', cha', wej, loS, vagh, jav, Soch, chorgh, Hut, wa'maH
Russian: Odin, dva, tri, chetir, pyat, shest, sem, bosem, devyat, desyat.
Chinese: Yī, ér, sān, sı, wu, liu, chi, baa, jiu, shı.