Very appropriate to the odds given for Tottenham. Many factors influence it as you say. Even Tottenham have never lost 4 previous matches in the EPL. There is great potential for Tottenham to really win tonight's match. Son Heung-min performance has been very good this season, of course that will add to Tottenham's confidence that they will win by more than one goal.
Sheffield United is a weak team, they have no chance to win against Tottenham. Based on the line up, Son will play as center forward, he was able to score 3 goals against Burnley, so I believe he will score many goals too in this match.
Yeah there is nothing we doubt about Tottenham, they are on fire and playing at home clearly their chances of winning are very high & Sheffield had no way to contain it. The odds for Tottenham are low but I will add it to my parlay list at least 6 teams with total odds @6 Tottenham, Liverpool, Manchester City, Newcastle and BTTS for Manchester United, Fulham is under consideration because their opponents today are a weak team and Luton is one of the candidates for relegation.
Your parlay bet is quite safe except you bet Newcastle to win against Brentford, they were suffered 3 losses in a row and it's not looking good. But I hope you can make some money from your selections, good luck.