Google decides if your ads are relevant

If your landing page and your ad copy doesn’t show relevance to the search keys.

It will also decide if your bid is accepted.

You won’t know anything until get a click.

For our market there are lots of people bidding on say HL7.

You can bid a daily limit or a weekly limit.

If the competitors use up their budget in the morning we could get cheap clicks in the evening.

Our budget can be used up quickly in the morning.

Google’s algorithms are fairly opaque. See Open versus Closed Systems