My first recommendation, if you’re just beginning and doing puzzles, forget the clock. It’s easier to learn a thought process and then get faster at it with practice. Not one I have used, but chesstempo is a highly regarded site for practicing tactics as you can tailor a training regimen. I use an app on my phone called chessimo. It is a one time cost, but it starts out easy in the units, but it repeats earlier units. You can set how much time yuu have for the initial puzzle, but it gets shorter in future units for the same puzzle so you build pattern recognition.
Dan Heisman’s a great resource for reading about thought process improvement. Here is an article regarding how he thinks of speed chess as a training tool - https://www.chess.com/article/view/is-speed-chess-good-for-you
I appreciate the outline of the time issues that Princess discussed. I know from my puzzle practice, that I usually miss my target times for completing puzzle, though usually not by too much. Usually the quicker I am, the less I see the board. A true matter of finding the right balance. So to start, if we were playing 5 minute Blitz, how quickly should we be making moves? So at 30 seconds per move, that is only 10 moves. What is a realistic goal or target for U1600 Blitz players (seconds per move), and what are some methods to reduce the time in our decision process?