Can they enter just because the gave 24 hour notice
Generally quarterly inspections are ok and do not intrude on your right to quiet enjoyment. But the lease should state what type of notice you should receive and how far in advance the notice must be given. If the says the landlord only has to provide notice 24 hours before then this would not be a breach. If the lease is silent on the issue you should consult an attorney but it probably would only be a breach of a non-essential lease provision.
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