Even if your sauce is nice and thick, it's still very important to drain your cooked ground meat, pasta, and vegetables thoroughly to avoid adding excess liquid to the lasagna.
See Also
Is It Okay To Boil Oven-Ready Lasagna Noodles? - Tasting TableWhenever I make meat lasagna the layers always fall apart. Any ideas on how to get them to stick together better? ~ Chani Czeladnicki - Kosher In The Kitch!Can You Boil Oven Ready Lasagna Noodles - All Roads Lead To Italylasagna - Wiktionary, the free dictionary