The phrase "approximately monthly" is correct and usable in written English.
It can be used to describe an event or action that occurs roughly once a month, without being exact.
Example: "The team meets approximately monthly to discuss project updates and progress."
Alternatives: "about once a month" or "roughly monthly".
Participants in both groups completed measures of vocabulary and comprehension approximately monthly.
Starting with SCOPe 2.02, we are also producing periodic updates that add newly released PDB entries the classification (approximately monthly).
Samples of ground water, tile drainage water, and stream water were collected approximately monthly over the 2003 field season and analyzed for NO3 N and NH4 N concentration.
Indoor and outdoor concentrations of formaldehyde and 30 other VOCs were measured approximately monthly during the first year of house operation.
Fish were sampled approximately monthly to monitor growth and determine whole body lipid level, gender and the state of sexual maturation.
Starting with this release, we will produce periodic updates (approximately monthly) that include confident automated classifications of newly released protein structures.
The frequency was regular and occurred about monthly for approximately 3 years.
It would maintain the approximately $44.5 billion monthly rate of purchases of longer-term securities in effect since Operation Twist started last September.
With the proposed network, we show that one of the regional DC's could be eliminated and distribution costs would be reduced from 12%to3%3% of the Net Sales (approximately a monthly reduction of $574,000 in distribution expenses).
The interval between PE sessions varied from once daily to approximately once monthly.
Google has approximately 12 trillion monthly searches, which dominates the internet search engine market to the tune of approximately a 90% market share, including over one billion YouTube users and 500 million Google Plus users.
