Under the Old Covenant, the Urim and the Thummim were used by the High Priest to ascertain God's will for instance. The Urim and Thummim were gemstones carried by the High Priest of Israel on the ephod / priestly garments. Joshua was to receive answers from God from the Urim through the High Priest, Eleazar (Nu 27:21). Gideon found God’s answer through the dew on the fleece, but the ground on which the fleece was placed was dry (Judges 6:36-40).
In Acts 1 vs 26, Mathias was chosen like this :
23 So they proposed two men: Joseph called Barsabbas (also known as Justus) and Matthias. 24 Then they prayed, "Lord, you know everyone's heart. Show us which of these two you have chosen 25to take over this apostolic ministry, which Judas left to go where he belongs." 26Then they cast lots, and the lot fell to Matthias; so he was added to the eleven apostles.
Please note that in this account, the Holy Spirit had not yet filled the Apostles when they used this 'cast lot' method to pick the next apostle. They were still in the old covenant. Think about it. I know you are going to jump up and say it is in the Acts, so the apostles must have the Holy Spirit already. Well, wait, the Holy Spirit came after this cast lot affair, only from Acts 2 onwards.
Some Christians do use the open door and close door method to pray for guidance –in fact, it is just like the fleece method of Gideon. There is no guarantee that God is obliged to follow the old covenant way of finding God’s will. We who have used this method for guidance have found that it does not always work 100%. This is the inadequacy of the old covenant.
The good news is that God has provided a much better covenant to give guidance today :
Romans 8:14, the sons of God are led by the Spirit of God.
Gal 5:18 :But if you are led by the Spirit, you are not under law.
When we are led by the Spirit, we are automatically not under the law. It is mutually exclusive, that is, we cannot be under both law and Spirit at the same time. Either the Spirit leads us or we are led by the law, the old covenant way through methods like the Urims and Thummims, cast lots or fleeces such as open door/close door.
The old covenant saints had to rely on methods because they were not born again and had not received the Holy Spirit to guide them. They were not sons of God yet.
For His sons and daughters, God leads by the Spirit. Rejoice, we who are born again are sons and daughters of God. We have a much more glorious way of guidance from God now. All because of Jesus. Praise God.