וַיִּקְח֞וּ מִלִּפְנֵ֣י מֹשֶׁ֗ה אֵ֤ת כָּל־הַתְּרוּמָה֙ אֲשֶׁ֨ר הֵבִ֜יאוּ בְּנֵ֣י יִשְׂרָאֵ֗ל לִמְלֶ֛אכֶת עֲבֹדַ֥ת הַקֹּ֖דֶשׁ לַעֲשֹׂ֣ת אֹתָ֑הּ וְ֠הֵם הֵבִ֨יאוּ אֵלָ֥יו ע֛וֹד נְדָבָ֖ה בַּבֹּ֥קֶר בַּבֹּֽקֶר׃
And they received of Moses all the offering, which the children of Israel had brought for the work of the service of the sanctuary, wherewith to make it. And they brought yet unto him freewill-offerings every morning.
וַיֹּאמְרוּ֙ אֶל־מֹשֶׁ֣ה לֵּאמֹ֔ר מַרְבִּ֥ים הָעָ֖ם לְהָבִ֑יא מִדֵּ֤י הָֽעֲבֹדָה֙ לַמְּלָאכָ֔ה אֲשֶׁר־צִוָּ֥ה יְהוָ֖ה לַעֲשֹׂ֥ת אֹתָֽהּ׃
And they spoke unto Moses, saying: ‘The people bring much more than enough for the service of the work, which the LORD commanded to make.’
The Torah specified exact measurements for nearly every part of the Mishkan and all the tools - the amount of gold & silver and the dimensions of the altar, etc. I assume that there was a head person (or a few people) in charge of inventory. If each day, people were bringing more items, didn't someone tell the people who brought something, "listen, please tell your shevet (or whomever) that we are almost at the limit of item X. Don't bring us so much because we will have too much" ?