How many "sevens" in Revelation?

The author of the book of Revelation has grouped many things into sevens. But how many times does the number “seven” occur? By counting links in the table below, and ignoring repeated sevens of things in the same verse, the number obtained is seven times seven, or 49.

Explicit sevens	References
churches	1:4; 1:11; 1:20 (2)
spirits	1:4; 3:1; 4:5; 5:6
candlesticks	1:12; 1:13; 1:20 (2); 2:1
stars	1:16; 1:20 (2); 2:1; 3:1
lamps	4:5
seals	5:1; 5:5
horns	5:6
eyes	5:6
angels	8:2; 8:6; 15:1; 15:6; 15:7; 15:8; 16:1; 17:1; 21:9
trumpets	8:2; 8:6
thunders	10:3; 10:4 (2)
thousand men	11:13
heads	12:3; 13:1; 17:3; 17:7; 17:9
crowns	12:3
plagues	15:1; 15:6; 15:8; 21:9
vials	15:7; 17:1; 21:9
mountains	17:9
kings	17:10

Other things are given in sevens, although not explicitly. For example, there are seven “beatitudes.” The word “earthquake” occurs seven times. More examples are listed by David Field. [1] The table below lists seven references to God’s prophets, seven references to earthquakes, references to seven beatitudes, candlesticks, references to Christ’s sword, Christ’s blood, the book of life, prophecy, day and  night.

Implicit sevens	References
God’s prophets	10:7; 11:18; 16:6; 18:20; 18:24; 22:6; 22:9
“earthquake”	6:12; 8:5; 11:13 (2); 11:19; 16:18 (2)
“blessed”	1:3; 14:13; 16:15; 19:9; 20:6; 22:7; 22:14
Christ’s sword	1:16; 2:12; 2:16; 13:10; 19:15; 19:21 (2)
candlestick	1:12; 1:13; 1:20 (2); 2:1; 2:5; 11:4
Christ’s blood	1:5; 5:6; 5:9; 5:12; 7:14; 12:11; 13:8
the book of life	3:5; 13:8; 17:8; 20:12; 20:15; 21:27; 22:19
prophecy	1:3; 11:6; 19:10; 22:7; 22:10; 22:18; 22:19
day, night	4:8; 7:15; 8:12; 12:10; 14:11; 20:10; 21:25

“He that hath an ear, let him hear what the Spirit saith unto the churches” occurs seven times, in: 2:7; 2:11; 2:17; 2:29; 3:6; 3:13; 3:22.

References

1. David Field. The Seven Blessings of the Book of Revelation.