An interest question quoted in the badei hashulchan is regarding what one should do if he is unsure if 6 hours have passed. Do we say that this is a straight forward rabbinical doubt, and one can be lenient, or do we say that this is similar to davar sheyesh lo matirin, something which will be permitted anyway later on where bitul does not apply now because we can allow it without bitul later on.

However others say that davar sheyesh lo matirin does not apply here. Based on the TZLACH quoted in P TESHUVA s.102,one could say I want to eat milk now and later, davar sheyesh lo matirin would be on one item , eg. eggs laid on yomtov which can be eaten afterwards. Here I want to have milky food now and later on.

kol tuv

Yitzchak Chaim Dovid Cohen

I recall a similar question regarding a Muktza item on Shabbos that became mixed with others, e.g. a chair that became a bosis due to something placed on it at the commencement of Shabbos & later removed, but it was in a mixture - I want to use the chair today on Shabbos AND tomorrow, so the s'voroh of "why use it today - wait till tomorrow" does not apply.