Yet another game where I dominated, but missed all the forced checkmates.

Wait...did you give your opponent extra time?

It says your opponent used 0.0 seconds on moves 17 and 18. After move 16 your opponent had 16.0 seconds left on the clock, but after move 18, 50.1 seconds.

I have time donation disabled for rated games because when people tried to give me extra time and I hit the +15 second button myself to give that time right back, they never took the hint. If you give opponents extra time without them asking then you deserve to be flagged from a queen down.

Yeah, whether you miss forced mates or not, you should not end up material down in such a situation. That's the real problem here.

I fell ya I miss force checkmates ALL THE TIME!!!!!!!!

"Wow, look at all those fun buttons!"

Why not keep your eye on the enemy king ?
Be the king hunter-killer ...

For instance, consider the following -

Maybe you even lost "because" you were looking for forced checkmates sequences instead of just playing simple moves but efficient to realize your domination.

@CARLSENisBack @Tuliptonite @pointlesswindows
Thank you for the advice about longer games, but I think I will stick to 5+3 blitz. I originally created an account on this website because I wanted to be able to get good enough at chess to beat my friends 100% of the time I play them when I play them OTB. They get impatient if I take too long to make moves, so I picked 5+3 blitz to mimic that impatience.

@Tuliptonite You are right about the time thing. While winning by checkmate is more satisfying, a win is a win. I think I will stop giving my opponents extra time.

@Talep I took this piece of advice you gave to heart in these games below. Unless I spot a mate in 1 or 2, I will instead use a dominant position to force an "endgame I can win blindfolded."

Another example is this game. I realized that, despite the fact that I was dominating, with a rook up, I might lose hold on my lead. So I decided to force a queen trade, allowing me to enter an "endgame I can win blindfolded," where I had no rook but he didn't, and I had a better pawn structure.

Even if you're only interested in specialising in blitz chess, it's widely agreed that playing slower training games at 15+10 or slower is something you still want to be doing from time to time. Some concepts take serious time investment (during a game, or in post-game analysis/self-study) to sink in, and then once you have that core understanding speed comes with practice. Of course blitz is fun at any level, so don't think I'm suggesting you put 5+3 aside.

That first endgame would have been scary to convert in a time scramble, if you ask me. After 47. Rxh7 the connected passed pawns can't be stopped, except by perpetual checks, and Black somehow manages to draw thanks to White's awkward positioning. In the end, you win because you promote with check. If your pawn had been on the g-file instead of the h-file, Black could promote with check and you'd have a nightmare Q v Q endgame (again, a technical draw).
Then, after you promote and remove Black's passer/queen, Black has no legal pawn moves, which can lead to stalemate scares.
Fortunately you were never in time trouble. The most comfortable endgame, though, would probably have been after 34. Rd7, which forces Black to give up a queen for a rook. Spending more than two seconds for a chance to see that tactic would have been well worth the investment.
Similar story with the second game where 31. Qd5+ is good, but 31. Re1+ is even better.

I don't think your stated approach is a bad one: if you know how to win won endgames then you only need to emerge from middlegames with the smallest advantages, which makes it that much harder for your opponents. But technical wins can still require precision, and I would say it's more painful to blunder a winning position the later in the game it happens.
(Which is more embarrassing? Blundering a piece in the opening and losing 30 moves later? Or being up a queen in an endgame and giving your opponent a stalemate? I'd say the draw stings much worse than the loss, at least in informal games with people you know. On the other hand, 'accidentally' blundering into a forced draw can be a diplomatic way for you and a lower-rated friend to both save face: it's very easy to pass off as a sincere miscalculation, which should be done only with show of rancour sufficient to preserve good humour and no hint of lingering resentment or suggestion of a rematch!)

In these particular positions you could have won even more material in the middlegame with tactics, but of course that won't always be the case in other games, certainly not when you play much stronger opponents. As such, focusing your general strategy towards obtaining technically crushing endgames and smoothly converting them may be better for your long-term growth as a chess player, compared to an approach that favours the fastest, rather than the simplest, path to checkmate.

I don't agree with tuliptonite regarding the first game. I think you played the middlegame very well (for your elo) [your 29th move, even if it didn't loose, was quite surprising though. Queening by taking a rook is rarely bad ^^]. Your endgame technique with a rook up wasn't so great, cause you underestimated the power of the connected passed pawn, but it is very understandable for your level. Your opponent didn't have the technique either to secure the draw when it was possible.

The second game i'd say you also played well the middlegame, until you blundered a rook. But you had already so much material that it didn't matter. You could have exchanged queens earlier though, for instance on your 23rd move (with a rook and a piece up).

I agree though that playing longer time control is useful to progress in shorter ones. You get used to play "better" games, so for instance you play more often difficult endgames than in blitz (and you improve your technique there). You also have to rely less on your opponent blunders which force you to find better moves.